The 4 inch moderns arent even in scale proper with the 2.5 classics if you're going by generations scaling. 100% not if you're going by the official height charts where they're technically supposed to be the same height in both classic and modern era. This is further distorted by the fact that post generations the classic designs limbs have been made slightly stubbier save for a few characters, and some of the classics characters are based on the genesis art or generations art. Some cases like buzz bomber and crabmeat aren't based on either classic or modern but instead are based on the lost world designs. This isn't even going into the REALLY weird stuff like the accessories where they're all scaled for the 2.5inch figures but only included with the 4 inch ones, save for the chaos emeralds which are scaled for the 8 inch standalone collector line figures.