Rich, that's about right re the change from a 48 to a 52, even on the same inches the 48 is easier to spin up and the 52 will roll better!
I'm riding 49x14 and it spins along nicely, Ian, try it, you'll be fine. I was riding 50x14 in the C's, changed down towards the end in May, it helped. (FYI just did the pursuit and kilo on 50x14, Sprint/flying 200 + Kierin on 50x13)