I covered a lot of ground in Europe in 2 weeks before going to my Premat program, and it was both worth it. 9 weeks is a long ass time, and 5 weeks isn't bad at all in terms of spending time in Europe. The premat at my school was soooooo fun. We studied and it helped a little with first year but it's not that big of a deal academically at least.
The biggest reason to do it, I think, is to get adjusted socially to medical school. Premat gives you a low pressure environment to meet people and go out and party, etc., and get settled into your new home before school starts. It's real nice to have a social system in place. I made a crap load of friends during premat and it was so much fun that it helped with acclimating to 1st year big time!
I would do premat at my school again in a flash... ask around the people in your school whether or not it was worth it (academically and/or socially).