You must be kidding me. Have you owned both wheels? Having less buttons is no reason to begin with. G25 shifter is one lousy shit without ANY resistance if not modified.
You can do the same resistance mod on G27 shifter, which it don't necessarily need while G25 do. Also, G25 sequential sucks after you have done the resistance mod, hardly even works.
Now there is a huge steering smoothness difference. G25 vibrates a LOT, because of the gears. G27 is has a huge improvement with it's new gear designs.
Also G27 has had some fatness to it's wheel, while G25 wheel ring is one thin POS.
G25 makes annoying ass rattling noise which can be heard from other side of the house because it's so deep. G27 barely makes any noise.
I sold my G25 long time ago to my friend, and has been testing both G25 and G27 side to side. I laughed at how shit G25 felt compared to G27, because I remembered that it was better.