Right now getting another 10-20 progun senate seats (regardless of which party they belong to) would be worth 100x more than the presidency. The senate is currently full of gun grabbers like Nelson. The House is IMO safely pro-gun (to the point that it will completely block all gun control in its current state) but the Senate is anti-gun enough that we have a very hard time making any headway. RINOs are to blame as much as the Kennedy's and Feinsteins.
Another 20 pro-gunners replacing antis or neutrals in the Senate would unleash a tidal wave of pro-gun legislative action in my estimation. Who the president happens to be at the time would be irrelevant IMO- even the grabbers are largely pretending to be pro-gun and would be afraid to give the NRA lots of campaign ad material. Remember what the 4 horsemen picture did for Kerry. You couldnt go near a range, gun show or gun store without seeing Kerry coming for your guns lol subtle.
My only opposition to the Dems at the moment (and this is a pretty huge issue) is that a majority would put all sorts of horrible people into committee chairmanships. Beasts like Schumer, Kennedy, Feinstein and Boxer would all be heading very important committees like judiciary, defense, ways and means etc. This would allow them to start tucking nasty stuff into appropriations bills (like we currently do to screw with the ATF), blocking pro-gun SCOTUS nominees, etc. They would all gladly do it and then go home and brag to their constituents in leftitst, antigun cesspools like MA, CA and NY. We are IMO one justice away from having a pro-RKBA, pro-Individual supreme court, which hasnt been the case since the 1920s. The worst thing we could do would be to throw that away by losing the Senate in 06 or 08.