This is one of the "duh" things, but it needs to be experienced to appreciate:
I have two bikes: a folder with 20" wheels and Surly LHT. During the winter the
folder experienced the most use - commuting to work. When going down a hill
on the folder, at 40 km/h one is thinking about writing his last will, at 50 km/h
one reviews his life in a flash, and at even higher speeds...what higher speeds?
Yesterday I took the LHT for a longer country ride (the first of this year) and when going down the hill at 55 km/h the ride was so solid and stable it didn't feel fast.
I don't want to put down the ride of a folder. I enjoy riding my folder even in a hilly terrain on longer rides. Just the difference in the stability and ride solidity is so profound...