I have a large cabinet saw and a TS75/MFT-3 and the last two projects I have made I did with limited/no use of the TS -- this is for furniture --one desk and two cherry 5 shelf bookcases. The Parallel Guides work surprisingly well and are very, very accurate once calibrated. The cuts from the TS are very near glue ready and it was a breeze to cross-cut the big thick slabs for the tops of the bookcases and the 32 inch wide desktop with the TS75. Having both types of saws, I have options. But honestly the speed, flexibility and accuracy of Festool has greatly diminshed my need for the large cabinet saw. In fact it has so much stuff on it now (clutter, furniture parts, etc...), it would take some time to clear everything off to be able to use it. I am trying to make more and more without using it and seeing what my limitations are for what I do. So far I have not come across any...maybe the speed of setting a rip fence vs. adjusting the guides is one big advantage, but so far I have been able to easliy replicate what I used to do on a tablesaw with my TS75 and other Festools. and having the dust collection and ability to store tools away in a small footprint is a real plus. I may very well end up selling my cabinet saw at some point and regain all that space...what a treat that would be. But I am also going to continue to build some other projects with just Festool and see how it goes.
Good luck with your choice, but it sounds like your space constraints and need to move tools in and out of locked storage would lend itself to the TS55/TS75 option.
Scot