The goal should be certifying ASAP, training on radar gives you another chance to wash and it gives you almost no advantage in transferring. If you have an interest in radar then by all means do it, but if you just want to get to a specific facility as quickly as possible, go to the best staffed tower-only with the quickest checkout times so you have the most chances to play NCEPT roulette. I was in and out of my level 5 tower in 20 months from day of arrival to reporting to the one I wanted. Three of my classmates are still waiting to check out on radar at a 7, with at least one not even to RTF yet...
I agree, but I really think it depends on the facility. I know people who trained on level 7 up downs faster than people at level 5 towers. It's more about the # of trainees in the building, how fast they train, what they consider trainable traffic. Right now, none of that even matters because there is no training in sight.