Look at Van's Blather here.

Kyle Boatright wrote:
In talking with Van's, they really thought they would have quite a few
customers for the RV-9 who would use the 0-235 or 0-290. Sure, there are a
few, but there are far more guys bolting on the 0-360 @ 180 hp, which is 20
hp more than what Van had in mind when he designed the airplane.

That sounds a bit like the story of the RV-6. I thought it was
originally intended for the O-320, and as more and more builders were
apparently successful with O-360 installations, Van designed the RV-7
with that (among other changes) in mind.

There is an old Tony Bingelis article about the pros and cons (mostly
cons... weight, fuel flow) of bigger engines. Apparently a lot of RV
builders missed that memo... Or you could say it is a credit on the
basic design that it accepts increased power so well.

I think RVs are great airplanes although I don't want one for my own.
Apples and oranges thing I guess.