Slightly correct actually...
Nah. If the only thing to increase was difficulty then your reward per round on slush pool would not change. You'd just find fewer blocks...
Original statement was either 'correct' or 'incorrect' - mathematics knows of no 'slightly correct' - unless you bring in quantum theory...
Edited post to clarify that I was responding to your statement about difficulty not affecting slush reward per round.
Sorry to be pedantic:
...
2) Pool hash rate is shrinking proportionally to the network (IE: Network grows 30%, pool only grows 20%) => Lower rate of block finds, you get a smaller reward per block.
I've bolded the one that is most likely given the current mining climate.
...
Your bold'un is still not quite right.
As long as your hash rate increases proprtionally with the
pool hash rate, then the no matter what happens with difficulty or
network hash rate, your block reward will remain the
same. You might find fewer blocks however but your block reward
only goes down if you don't match the increases in your
pool rate.