Would it make sense to have a payment system in which the user who solves a block for the pool, gets an additional reward, i.e. 0.5 BTC or even 1 BTC?
This way there would be extra incentive to join, being given a shot at hitting a small jackpot without having to to mine solo against astronomical odds, while not taking away too much from the pool in relative terms?
I don't know if this has been discussed or done before, or even is being done... I think it could do well for the dynamic of a pool.
No.
All it does is increase variance.
Yes, I figured that the idea must have been explored before. From the perspective of the pool operator, i.e. you, it should make not much of a difference, in terms of earnings.
True, the 'jackpot feature' would attract users on one hand, but also, on the other hand, tons of speculation and hopping in and out... didn't think of that.