Jiminy Peak is much easier than Quabbin in my opinion, particularly as a 5. There is one major climb at Jiminy and the rest of the course is flat to rolling. As a 5 you only do two laps, for 60km, so only twice up the climb. At Quabbin everyone did the same course so it was 100km, with much bigger rollers and it was damn hot on the weekend!
Also, frequently there are heavy headwinds at Jiminy so its hard to get away, last year everyone stayed together until the final climb to the finish, this is where the hammer went down so you need to be well positioned and preferably on a wheel as you turn onto the climb.
Thats my 2 cents