Graham,
4. I meant using the sliding table on the CMS not on the MFT, sorry Senior Moment! I don't have the MFT (don't have room and already have a workbench with side and end vices). The MFT would be useful not just for cutting but as a general work bench if you don't have one but not essential if you have CMS and rail. The fence is totally solid, once set no movement at all. It has detents at various preset angles, and will always go back to exactly 90 degrees. In use there is no deflection either when crosscutting or ripping. Best to try and see one for yourself but in my opinion the fence and sliding table are the real stars of the CMS (I believe they also fit on the MFT/3).
5. Although the 75 is heavier than the 55 I have not found it a problem. I am of small stature with small hands but can manage the 75 on a rail one handed with no problems. Again, if you can get along to a Festool reseller and try the weight for yourself.
6. I am a weekend woodworker so don't do more than a day a week in the workshop. I have filled the 33 twice in a year. If you do the same type of work the 22 would be fine. I have a personal quirk that nags me if I go for a small when I really wanted the large even if I don't really need the large, so I went for the 33.
7. I also have the Metabo Duo, it does not get a lot of use but I think the Festool hose will fit directly, I will try it tonight and report back tomorrow.
Regards removing the riving knife, you have to lift the saw table out of the leg module (release two large screws). Turn the table over, plunge and lock the saw into the halfway position (as if changing the blade) remove a clip, undo the allen screw that holds the riving knife in place and remove it. Release the saw back to the normal position turn the table back the right way up and secure into the leg module again (two large screws again). Probably takes a couple of minutes. To put the riving knife back is of course the reverse of the above procedure, although so far I have not got the knack of getting it in the right position first time so it takes me a little longer.
Hard to say about the dust extraction, I always use both hoses. The dual hose has two different dimensions, one large one small. The large one fits on the saw underneath the table, the small one fits on the saw guard above the table. With the router it is reversed, the large one fits on the back of the fence above the table and the small one on the router below the table. If you did not have the dual hose and only had the single hose then you would have to choose whether to mount it above or below the table. Maybe if you decide to go for the CMS and CT then you will get a hose with the extractor, try one hose and if it is a problem buy the dual. You wont waste the hose that comes with the extractor because you can use this for the saw when using it with a rail.
Martin.