As an "old guy" founder with multiple exits, may I suggest you consider reframing the question in your own mind, perhaps to something like "If I join an 8-person startup, what are the daily qualities I need to exhibit to become indispensible to the team, and maximize the chances of not only riding this pony across the finish line but becoming well-positioned to leverage that success into even bigger and better things going forward?"
A couple of quick observations:
1) It seems unlikely that the CEO you decribe (5 decent exits, and another $2M series A) got that far by screwing people by any objective measure.
2) I've never met a rockstar who (as far as I know) worried a lot about getting screwed... they knew they could walk into a better gig any day if they weren't getting a fair shake.
3) They probably won't have too much wiggle room on their first offer, anyway. Sounds like they have enough experience to know what it takes to attract and retain a good team. So if you feel you can do "a lot" better elsewhere (or where you are) then that would be the right choice for you.
4) It's worth considering that it's one possible stepping stone on your path. When I joined Xilinx very early, I was pretty darned sure I was worth a lot more than the stock I got. That said, it was an awesome education on thriving in a frenetic startup environment with exquisitely talented peers, and fwiw that seemingly-meager stock offering bankrolled my next deal, which bankrolled the next one, etc.