Aye, I'm not sure how big a market I'll have at the moment. The goal is actually to build a community somewhere between the two, as there are parts of both I don't like. I'd like to promote constructive criticism rather than fanboy comments, and do away with ratings (which are my main problem with 500px). I also find that none of these sites have yet figured out how to help you discover great photos, which I'm hoping to find a better solution for.
I'm trying to get the basics up in the next couple of weeks so that I can start working on more specific features :)
I'll have multiple file drag & drop in for the very first release, but after that I'm hoping to implement the ability to import from other services. And further down the line I'd love to be able to offer Lightroom/Aperture plugins for exporting photos directly to the site.
HN will be one of my first stops when I launch it, as I'd like knowledgeable beta testers!
I'm trying to get the basics up in the next couple of weeks so that I can start working on more specific features :)