The way I look at it:
No need to push it in the beginning, if everything works out great and they want to keep you theres plenty of room for negotiation later.
If you only look at %gain, I think the most extreme returns will be found in the groups that take the most extreme risk.
Extreme risk you according to normal rules wont be allowed to take on in a bigger firm.
If you compare risk/reward I think almost every trader at a big firm will beat most...
Where do you get to keep it?
Not saying that its not possible somewhere, but I would say that you will usually not.
The exchanges I know of will treat this as a new entry.
Feel free to enlighten me.