The leg extender removal mod on TFA was very easy to do, and solved the scale issue to my eye at least...
I like the new look of TLJ Finn, but it's close enough to TFA so that I can't see needing a new figure. If they fix his expression in the new release, however, I could see going in on buying a parted new sculpt if the price were right.
Acquiring a parted out new sculpt will definitely be in my plans, as well. I was never happy with the released sculpt on TFA Finn. Preferred the proto sculpt.