... what would be the bonus for him?
I've wondered about that for a while too! -ck, any easy way to estimate?
It's always been a small reward for small miners. It's approximately equal to the minimum payout threshold for the pool so if you were always below threshold, it would start putting you into the next payouts list.
I've been tempted to increase it but if I increase it too much that would start biasing towards the biggest miner, taking away from everyone else and we only really have one very big miner.
And just for the record, here is the equation:
herp = sqrt(MIN(sdiff, network_diff) / diff) * diff / 2;
Current network diff is 5.3 trillion, and being an S9 his mining diff would have been about 10k.
So the block solving share would have counted for about 115 million HERP when a normal share at 10k diff averages 10k.