I agree with much of Danny's comments and somewhat disagree with others. With Festool operations that involve the MFT, you also have to be thinking logically step by step, and if you have to redo something, you also have to take the time to change back to a former setup. Recently I wanted to make five large drawers (~24" front to back and ~33" wide), and due to the design of the HD (250 lb rated) slide and the large storage unit (7 ft high) into which those drawers were to be fitted, the overall width dimension of the drawers had to be exact within 1/32 inch for everything to work correctly. Because I planned to store paints, tools and auto parts in/on these drawers, I wanted them to be very strong. So I wanted dovetailed or some other interlocking joint, and the 3/4" birch ply bottoms to be full perimeter T&G joints. Again, the dimensions of the drawer frame pieces and ply bottoms had to be very exact. As you may know, it can take a bit of fiddling when setting up a lock joint bit or dovetail bit in your router table, and this was my first time trying to use a JoinTech setup (without any setup gauge blocks). I only had 3 pieces of cutoff stock to use for setup, and obviously, once I cut the actual drawer frame pieces to length for making the joints, I would either get them right or have to buy and prepare new stock. As a result of my inexperience with these router bits and the JoinTech system (similar to Incra), I had to repeatedly go back to my MFT/TS 55 setup to carefully cutoff the ends of my setup stock then go to the router setup. In sum, unless you have more than one MFT, and / or you are more skilled and lucky than me, you are likely to have to go back and forth between various Festool setups when making a project such as the one I just finished. With the help of my wife, I installed all 5 drawers last evening and to my surprise and deligh, all work quite well (thanks to Festool, Woodpecker's and JoinTech precision). After tinkering with my router/JoinTech setup, I proceeded to use half-blind dovetail joints at all corners of the drawer frames.
If you can afford the cost and the space, having 2 or more MFTs is a big plus because you minimize the need to tear down one setup to build another. For example, you can keep one MFT ready to go with your saw, and another for routing or use of Domino or assembly, and if you mess up a component during a subsequent operation, you can prepare another piece of stock much more quickly and with less risk of loss of accuracy.
I suspect that after Festool releases its replacement for the current MFTs I'll be in the market to acquire one of more of the "obsolete" units.
And I will keep my Shopsmith. When using it as a lathe, due to its rather light construction, it is especially important to have sharp tools and to frequently and properly adjust the tool rest, and it the work is long, e.g. a baseball bat, to provide support of the workpiece near to the point of tool application to reduce flexure and dampen any vibration.
Dave R.