Captain Cadaver said:
Supplementary material such as some guidebook statements and the Super anime suggest that Grade 3's raw power is superior to SS2, not to mention being able to harness that much raw power just by gaining another form would go against the kind of training Goku and Gohan focused on. That said, I'd say no.
Well, Goku wasn't against transformations per se, he was against
those transformations as they carried impeding drawbacks. There's this theory that by eliminating the drawbacks of the SSJ, you open the gates to access the boost Trunks benefited from earlier on but in the "right" way, that is, your body doesn't change drastically. In the anime, iirc, Cell even stated that Gohan was comitting the same mistake as Trunks when he was midway in transforming into the SSJ2.
But yeah, granted, the DBS anime seems to treat the SSJg3's boost as superior and as Kenshi brought up, if the SSJ2 is only 2x, then that's likely the case. I don't think the boost needs to be exactly the same though... if the SSJ2 is the SSJg3 used in the right way, then maybe the less apparent physical changing meant a slightly smaller boost.