I am using TCS 3.5. This means I use unstructured FM 10 for PDF documents and RoboHelp 9 for help systems. I looked at TCS 4.0 and so far I have found the new version underwhelming. If I had structured FM or needed some of the new SSL in Robohelp, it might be a different story. But for someone who uses unstructured FM and webhelp, there's nothing really there there as far as I can tell. And no I couldn't care less about illustratror. One thing that may make me seriously consider upgrading to FrameMaker 11 is if Adobe fixed the bugs and feature gaps in the ExtendScript implementation in FM. However, I haven't been able to find out any information about that. Does anyone know?
I'd suggest downloading a trial copy of TCS4 and playing around on a non-production machine.