when you guys say heel down, do you mean playing with your ankles? i've tried, and if you want to get solid, consistent results from your feet, this is the perfect example of what not to do. I find that it is the right combination of leg and ankle movement that works best. playing with nothing but your leg and not moving your ankle (heel up, toe playing) will get you tired and in-consistent - when you play at a moderate rate you'll hit the kick with less force and when you try to go fast you'll be hitting it alot harder, hence you'll get inconsistent bass kicks. if you play with nothing but your ankles (heel down), you'll wear yourself out before long and you'll always be hitting at half the power.
i find that you've got to find a happy medium between the two. i have heard countless drummers tell me that playing heel down is the way to do it and i have no idea what their talking about. it wears your ankles out and never seems to hit hard enough.
i've always had the problem of my right leg hitting harder than my left when doing double bass, and my playing technique isn;t the problem, it's practice. you gotta practice at hitting both feet with the same force, for a long long time. and heel down has never worked for me. it's just as rediculous as playing lars ulrich style, with your toms straight up and down in front of you like your playing on a wall.