What is the difference in handling/suspension when using a 18" or 19" rear wheel? How can 1" effect the ride? I am trying to choose between YZF and WRF and this is just one of the concerns I have. Either bike will be a blast I'm sure, BUT I AM HAVING A HARD TIME MAKING UP MY MIND! Seems to me that a 19" would work better for offroad (through ruts, holes, etc...) but only MX bikes come with 19". Why?