The 9010 and the 9015 are the same unit only difference is the skimmer cup and $100. Your money is better spent getting the 9010 and the foam extraction cup add on for the same money.
There is no comparison when putting it up against a G1. Difference is going to be night and day. I had a G4 with sedra 9000 fully modded with meshwheel, gate valve, and recirc and the 9010 is keeping up pretty well to the G4 on a 110g ( community tank but more acros than any coral type ). Not necessarily better than the G4 but actually not very far off........ Considerably less noise and much smaller footprint ( allowing more room for refugium filtration ) make up for the slight performance loss in my case.