This thread might have gravitated towards comparing FDs with EP weich because a lot of folks say that EP weichs feel like other string's mittels. (BTW, I don't know the numbers, but the FDs feel thinner than EP weichs, which would make the EP regulars way fatter strings than FDs.)
Anyway, to answer your questions:
Tension -- on my bass, FDs and EP weichs are pretty close in terms of stiffness/tightness. So the regular EPs should feel stiffer. (I also have a regular set of EPs lying in my drawer for some years now - they've been in there ever since Pirastro rolled out the weich gauge ).
Arco in thumb position -- I think the jury has come back on this one: FDs are an EXCELLENT arco string all across the fingerboard. When you talk about the EPs (both gauges) being "boring" in thumb position, I know just what you're talking about. It's the main reason I went back to FDs.
Dynamics: as been pointed out, FDs won't crap out on you. If you want to play loud (arco), they'll play loud. If you want be sweet & subtle, they'll do that too.
Pizzicato, they are slightly less loud than EP's (even the weichs are the loudest strings I've had on my bass). But again, because of FD's superior arco performance, I'll adjust.