Hello ivanhoe, nice to see another participating member
This is a hard question to answer as I've heard many people rave about the MFT/3. In my experience though, I've had many mixed experiences. The short of it is that I don't think it's all what many make it out to be because there are just too many tradeoffs. Most of them inherited by it's design. I'll try to write down my thoughts and experiences below. Mind you this is my personal opinion and many might not agree.
It really depends on your use! On site, questionable depending on the precision you need/want in your work. In the shop, very nice!
You say you operate out of a shop mostly, and unfortunately I mostly work on site. So chances are much of this probably might not matter to you. But I'll just write my rant down down anyway and get some things off my chest
In a nutshell, like everything Festool, you'll need to buy a lot of additional stuff to get the most out of it.
For starters because it's meant to be a portable table it's rather small at 110cm x 72cm. But because it's so small you want (read need) something to extend it. Be it a home made solution, saw horse, one of the Festool miter saw extension wings or an extra table. I've seen most ending up buying a 2nd or even 3rd MFT/3 (for shop use). The internet is filled with modified MFT/3's because it's just too small.
So that's the first issue: Portable = small = you need extra stuff = multiple trips to go get the stuff = you guessed it, not so portable anymore.
The 2nd issue is that it's rather heavy to lug around. I've lugged mine with me on stairs a few times and it's been such a hassle I've decided I'm not doing it anymore. It's not unmanageable, but it can be a good workout at times depending on the location and the number of people around.
Lugging that table under the painter's ladder on a small stairs is quite a feat to pull off.
And like I said in my earlier point, you need to make multiple trips up and down to get all the extra's if you plan on cutting things larger than cabinet sized panels.
The 3rd issue is that it's not very stable. There's a lot of wiggle. And it only gets worse the more you set it up a break it down again. That's OK for power tools and small workpieces? But once you get a heavy piece on there, it starts getting wobbly real fast in my experience.
Festool offers a set of additional cross members to make it more rigid and these work pretty well I must say. But you need 2 sets to have them on all 4 corners to make it truly stable. This drives up the price and again, makes it heavier and heavier to lug around.
Stability issues = extra cross members = extra costs = extra weight = you guessed it, not so portable anymore.
The 4th issue is that it takes some time to set it up when you bring it with you. Once you get the hang of it, you can do it in a few minutes, but it can get old fast if you have to do it a few times a day in different rooms.
And the last of my complaints is the most serious one: maintaining squareness.
I can tell you right off the bat, forget about using it for precise angle cuts. There's just too much slop in the miter gauge. I think it's more geared towards approximate ballpark angle cuts.
The idea of using a flip down rail is really useful and quite ingenious I must say. It's the MFT/3's main redeeming feature. (Adapting it to Mafell/Bosch rails is easy as pie as well.)
When you rely solely on the components supplied with the MFT/3 you'd be wise to check the guide rail and fence for square at regular intervals, especially if you break it down and set it up a lot on site. Things tend to get bumped into and knocked around a lot.
Another issue is that there's a very noticeable flex in the fence where it's closest to your guide rail. If you exert pressure on your workpiece the fence will bend back at the point closest to your guide rail. I prevent this by putting 3rd party bench dogs behind the fence and butting said fence against these dogs. This guarantees square and that the fence wont bend on me.
Bench dogs are a great solution for both setting the bench up square and to make accuarate angle cuts. Get at least 4 (I got me 8). If not, you need a large square to align both the fence and guide rail. Using bench dogs however is a more fool-proof way that's both quicker and easier.
Again though, more components = extra costs.
The perforated top is great. Very versatile to clamp all kinds of stuff on!
There's a lot of great and solid ideas behind the MFT/3, but the execution is flawed exactly because they wanted it to be portable and in the process made too many sacrifices in the precision and overall sturdiness of all the components, resulting in a table that ultimately kind of fails at real precision work.
I don't want to be a negative Nancy. If you're in a workshop environment, the MFT/3 can be awesome for you!
In that case you can join multiple units together to make any kind of setup you want. You can add whatever extensions or modifications you like.
And if you live in the EU and invest in Festool's full range of power tools you also have access to the CMS modules where you can turn some of the power tools into stationary tools. Like turn the plunge saw into a table saw, turn the jigsaw upside down to create a mini bandsaw, turn a router into a router table.
That's some pretty awesome stuff, but again, with tradeoffs in capacity and precision.
So to sum it all up, if you work on site a lot, it works in certain circumstances and certain jobs, in others it doesn't perform that well. I don't think Festool has nailed it with this design, yet.
But if you have the room and you're willing to spend the cash for all the extra's, it can be really great!
For many guys time is money and they're both always tight, so it's often easier to just buy the stuff instead of making your own. However, I do believe that building your own custom bench, borrowing the good ideas that Festool came up with for the MFT/3 is something everybody should consider.
For my very modest home shop/shed, that's what I'll be doing in the very near future, making my own MFT/3 inspired clone out of aluminium extrusions. Something larger and sturdier but with the same features and some of my own.
But Jonathan, if the MFT/3 is so "terrible", why do you have one and what do you use instead? Well the MFT/3 is modified with a Mafell rail and a bunch of extra components for rigidity. It's now relegated to my shed at home and unfortunately my solution for the jobsite isn't any better than the MFT/3 but it is more portable. And as you might have guessed that's the main criteria for me.
I'm currently using my vaccuum with the Festool vac-sys on top and a saw horse when I need to handle larger pieces. It's still problematic at times.
Hopefully these experiences answered some of you questions. If you have any more, feel free to ask. I'm sure other members will chime in as well with their opinions