Enkei RPF1 issues with fitment?

[SirDigby]

So i'm real interested in purchasing these wheels. on the FOR SALE section there is a gentleman selling a set of 15's. he has the corolla brake upgrade and had issues with barrel to caliper clearance and spoke to caliper clearance. so i'm glad I came across this issue before I purchased them. (I plan to do brake upgrade in the future)
my question is; does anyone have this wheel in a 16 with the brake upgrade? i'm curious about clearance issues.
also, can anyone explain the weight differences? the 17 is 14.6lbs, the 16 is 13.7lbs but the 15 is only 9.5 or 9.9lbs so to go from 15 to 16 you gain 3.8lbs (or more) but from 16 to 17 it's only 0.9lbs. (???) wouldn't you be adding more material going 16 to 17 than 15 to 16? wouldn't the material be near the same?
has anyone fit the 15" PF01 wheels with the corolla brake upgrade?
again, weird weight differences: the 15 weighs 12.1lbs. where as the RPF1 is 9.5-10lbs. (difference of 2ish lbs) but 16 PF01 is 14lbs. and the RPF1 is 13.7lbs (difference of 0.3lbs)
I really like both of these wheels, and the weight difference is not that different on the 16's so that is probably the direction i'm going in. it's too bad about the fit with the 15's.