Coaxial connectors should be soldered. Keep an eye on your crimped connections as they're more likely to fail that with a soldered connection. I agree with Dave, that you should have a balun at the antenna. My Cushcraft 3 element tribander calls for a home made RF choke at the antenna end of the coax, and not a balun (although I think a balun would work just fine). The homebrew choke wouldn't require the purchase of a store bought balun. What does the Buddipole's owner's manual call out?
Let's try 17 meters, what do you say?