You are running like God in terms of finding blocks.

Going from memory, 1GH/sec in mid-June was expected to find 1 block every 90 days running 24/7.  And obviously, with every difficulty increase the expected number of days should increase. 

There's really no compelling argument not to join a zero-fee pool, aside from not wanting to participate in a pool that is nearing the 50% mark.

 Just make sure you have a backup pool to deal with the annoying DDoS attacks.