gladiusdei:
just trying to figure out the best choices to give a game the best chance of success.
If you build it, they will come. More than likely.
I think the choices you should be concentrating on are what's going to make things easiest for you to keep the game flowing, and keep yourself interested and sane.
The last SR game on RPoL I was a part of was pretty standard 5th edition, Metatypes from the core book only, but rules and equipment from everything else. Pretty standard in terms of player expectations, 3-4 posts per week, recommended posting conventions, etc, etc. The GM decided to take whomever wanted in and then group people up.
The game had 17 players and 15 completed characters and about two weeks of active IC posting when the GM ghosted due to what they later informed us was a combination of RL issues and perhaps biting off a bit more than they could chew.
That's not an unusual thing either.
So as long as you set it up so you can be in it for the long haul, keep the story flexible so you can bring characters in and out as players fall off the face of the planet (as always happens in every game) and you have to recruit more, I think your game will succeed as well as any, no matter what mechanical system minutia you decide to go with.