I can give you a little information on what happens when you do prune. I planted three cherry knockouts early in Spring of 2005 (I live in Nashville, TN). They took off and were very healthy. After they bloom, to me they look like they need to be dead-headed. However, most of the new growth starts at the tips where the old blooms are, so I would lightly prune and try not to cut off where there was new growth. This type of pruning can be very tedious. In the fall, I did not prune at all. In the very early spring this year (before any new growth) I did prune them back by about a third because they looked pretty bad (scraggly). When they bloomed, they were beautiful. After the first bloom, I pruned again. I will tell you that my next door neighbor and I bought our roses together in 2005 and planted them at the same time because we have an adjacent garden. She does absolutely nothing to her roses. Her's actually bloomed the second time much better than mine did -- more blooms and fuller plants! So, I think that I may prune back a little after it gets cold (when they are not growing), and then just let them go completely next summer and see how that does.