Zero experience with Festool. My Fein T-III is 7 yrs old or so. Love it. Use it for general clean up, but the main purpose is via hose to ROS, hand-held routers, belt sanders, etc. Collection of fine ROS sanding dust is outstanding - I have a 12-yr-old 5" PC ROS.
The one mistake I made when I bought it was corrected within 3 months - I spent the $$ to get the accessories to let me use the disposable bags. There must be some level of hell reserved for emptying fine sanding dust out of shop vacs.
When I started woodworking, I didn't know squat. I have progressed in 30 years - now I do know squat.