Pricing:
1) Phone deals can be done. You just have to convince the person on the other end you are serious and have a good reason for not going in person. Some just won't deal over the phone, those are the ones that steal fewer deals from competition.
2) I found Canadian Dealers not as good at negotiations that benefit the buyer. The Lund dealer at the boat show came across as a pro but I did not get into negotiations. The Lund guys were there too and helped out a lot. I too am thinking there are deals to be made. US dealers are worth calling for sure, they want business too.
Difference between Impact and Explorer:
Those boats did come across as very similar in feel. I am going to guess you already have the brochures with specs and you are different than me (I liked the Impact)
Go to the boat show (or if your lucky enough to have a dealer with both go there too) and pretend you are going through through your daily prep or fishing routine: are the rod storage compartments long enough? Where are your rods and tackle going to sit when you are not fishing? Will the kicker motor be rigged as you like / think it should be? KNOW what the options are and how they will look/operate, do not assume.