The big problem for making pool is shares check....
Example: If you mine 9-er chain and submit 6-er chains as share you'll get about 20 6-er chains in a hour.
Exactly! A miner properly optimized for short chains (to get the best possible reward from pool) would have low performance on 9+ chains. Sort of withholding attack from pool's point of view.
Looks like someone was stupid enough to make one of these... Ypool has come out with new share rewards:
6-chains are now worth .000976
7-chains are now worth .03125
8-chains are now worth 1
9-chains are now worth 32
10-chains are now worth 1024
God you gotta love fools and their stupidity and greed. Ya just F'd yourselves.