On my Cruiser which is the same as many models including the Tour II, the 26" upgrade lowerd the cranks and bottom bracket one inch and raised the seat one inch. The gear inches of course was raised enough that I am going to change the center and large chain ring to 38 and 48. I will probably replace the the rear sprokets with an 11-32.
I rode my Cruiser about 250 miles with the original 20" rear wheel. Do I like the upgrade most certainly yes. The main reason I bought it was to get the chain and RD further up out of the dirt and trash. I also found I can stand up easier, and my knees are not so much in my face while peddaling. Lastly for no good hard logical reason the trike just looks better.
Oh-----------and one final thing with a big back wheel and small front wheels I am alway going down hill!!!