Yup.
Half of the LS swaps should have stayed in the vette it came out of, honestly.
However:
I've been following vorshlag's ls swap kit progress and they said at the end of the day it's around 100lbs or so difference, but the weight distribution is much better making it not that big of an issue.
The LS Swapped BRZ might corner .05% not as well, but would make up for it in acceleration through the rest of the course. Hell, that's only 50lbs more than a good turbo/sc kit anyway.