Up until now, we have been version strict about using music that can played on Commodore 64 hardware. This can be a double edged sword, as it's hard to make this music sound palatable to modern ears, but if we can, there is obvious kudos to work within the limits of old technology. So what are your opinions? Should we relax this a little bit? Keep strict? Do an alternative soundtrack option like Cave Story?

All SID all the time! :D 

I'd stick with SID

I'd suggest to make retro-styled songs.

I guess it will be more pleasing to most listeners and it if it makes work easier for you, then I can only see advantages.

You could always "remaster" your sound to a c64 style later on and give the users the option to switch between the 2 sound-modes.

SID would deepen the whole aesthetic effect IMO. 

I dig what I have heard so far!  I especially liked that clip that showed the sunset and then there was music with it.

SID needs more love, but I'd be okay with an alternative soundtrack as well.

pure SID music, possibly dual SID since thats possible for things like the MSSIAH cart. An alt soundtrack option should wait until after release, if you decide on that

I always felt that the music of ID’s Wolfenstein suits these kind of games best. SID music is okay, but when too noisy I might grow tired of it. Something with a pumping base could be achievable with SID I suppose. But it requires a lot of skill to pull it off. The music should stay in the realm of retro pixeled games, midi can produce a lot of beautiful tracks. I am thinking of using a soundbank in combination with midi myself in my own games.