I agree that the difference has to be on the order of 20-30lbs.
As far as ride height, dropping your car an inch is no big deal IF you mean an inch from factory ride height spec.
But what if your car was already low before the swap?

Measure the ride height now compared to spec.
Heck---many thousands of car owners took advantage of the adjustability of torsion bars to lower there car a bit (1-1.5") with no ill effects.

If your worried about a SLIGHT change in tire wear, and you drive your car a LOT, then get it re-aligned