Is .blend a acceptable file format?

[Pingus!]

As I know .DAE, .SMD, and .OBJ are the most common files for rips.

But I'm wondering if .blend is allowed, as it seems that it's the most stable for vert shaded models with tons of clamping.

*.Dae or *.Obj are required as a base submission to the site. Without at least one of these, your submission will get rejected. As long as you have one of these, you are free to add whatever extra formats you want to your submission, just make sure you have either a *.DAE or a *.Obj(With it's corresponding *.MTL) included in your submission.