Yes you can. But watch out as long as your piece is on the front page, there's a bug that can cause the preview image to break when you update.

But since this isn't on the front page anymore, there should be no problem with updating

Cool, thanks for the advice. You can edit stuff after it goes up, correct? I might just put up the full color background version because it does look better.

Not that serious in my experience. If it's a piece with no outer AA it may get pointed out by some commenters but that's all I've noticed. You can always write in your description that you AA'ed against that background and have it there for that reason.

Edit: when in doubt, ask a mod

Yea, I actually just had it on a solid color of that as the background, but the site rules said to avoid solid color backgrounds when possible so I made it a thick outline. Not sure how serious people are about that rule since I'm new posting here!

the outline is rather extreme compared to the thickness of the figure, any particular reason for that?

I think the statue could use a bit more contrast to make the shapes stand out more.

Yea, I definitely see what you mean. The top side of his arm and leg look especially blocky to me, If I ever revisit this I'll look into that.

Ironic given my previous comment on your work, but I think you under-AAed a bit here - the AA on the shadowed parts is good, but the highlights have no AA and look blocky. They could use a little bit of AA, I think :] Your brightest highlight colour is similar enough to the previous colour that you could harmlessly move it inward a pixel in the thinnest areas, to make room for AA that won't make the figure thicker.