When I purchased, I went down and got approved through my credit union, so I knew the exact rate I qualified for. When I went to the dealer, they gave me the standard HD can beat that rate, blah blah blah... Then when it came back 2 points higher, they tried to sell me on why it would be better, blah blah blah. I told them thanks, but no thanks.
So the advise given to do your homework first is spot on, and it sounds like that is exactly what you are doing. Good luck and enjoy the new ride!