That’s not a bad idea to link artillery with mechs on a 1-1 basis for movement. Although, it might be obsolete if people start incorporating self-propelled artillery into the game. HBG is already making SPGs in his Axis Minors set.
A couple of house rules that my group uses:
1 - Defending Subs are allowed to submerge after first round of combat even with enemy destroyer(s) present. Basically, the attacker gets to roll with whatever he/she is attacking with, including aircraft of course. If they score hits on the subs, then tough luck. If they miss some/all of the subs, then the subs can submerge and escape the battle. I get the idea of destroyers cancelling the first strike capabilities of subs and spotting them for aircraft attack, but I have never liked the idea that a sub is “trapped” and can’t submerge just because an enemy destroyer is present. In reality, subs COULD still evade destroyers, it was just a little harder. Plus, I don’t like the idea of a single destroyer showing up with 10 fighters to wipe out a stack of subs. That just doesn’t seem right to me.
2 - Heavy Bombers get to roll 2 dice and get BOTH results. In combat, it is 2 hits (@ 4 or less of course). In SBRs, they get BOTH dice worth of damage, although I don’t add the extra 2 like with regular bombers. I think if you spend the money to research that tech, your Heavy Bombers should pack a bigger wallup. Rolling 2 dice and just picking the best one isn’t Heavy Bombing. That’s more like precision bombing or smart bombs which I think is beyond the technology of the time period of this game.
3 - Mechanized Infantry can “blitz” on their own. We just don’t think that mechs should have to be paired with tanks to take over empty territories. They still only attack at 1 so if they run into any enemy troops, then they may be in trouble but empty territories should be able to be exploited.