Well, speaking as someone who at his peak months ago, blew well past the 5,000,000 mark more than once (Is that bragging? I'm sure it will be perceived as such, 'cause you're reading it, and it's me posting it), I can safely say that playing this game in widescreen HD puts one at a slight (?) disadvantage over those playing in standard definition, with a 'fullscreen' ratio. The reasons being, the fullscreen aspect allows you to see enemies coming a split-second earlier (particularly the red ships) and with HD, the explosion colors really 'pop' that much more, and it can be blinding at times.
Sure, HD players can see each individual jack/mayfly a little bit better, but if you're looking for each one of these, you're probably about 0.2 seconds away from death. After hitting the six-million mark, I kind of 'retired' from the game and didn't play it again until the rust had set in and I acquired an HDTV. A couple weeks ago, I 'fell off the wagon' and was playing this nightly again, and even though I felt like my 'chops' were back in full form, I couldn't seem to break the 4,000,000 mark, and while I used to be able to hit 2.5-3 million with no effort, that's even a struggle for me now. No excuses, but I maintain that HD hurts you here, in a game where milliseconds are everything.
Either way, though, it's all about knowing how to instantly react to the variety of enemy attack waves, and knowing how to 'dance' with the various enemies, not (always) straight-up attack them. The game is constantly asking you to be simultaneously the ultimate aggressor and extremely evasive, and that's why it's still the best thing from a 'next-gen' console. No, seriously.
P.S. The Wii version could be transcendental, but I'm afraid it'll be an imprecise cash-in trainwreck, and maybe even largely dumbed-down.