I have a 2'x10' workbench that is pretty flat. Made of a steel angle iron storage shelf, with a kitchen counter top for a surface. It's flat to the eye, with about a 1/16-1/8" dip near the end of the bench, so I don't build there, I use that area for my cutting board.

I was all concerned about the wing coming out warped, but she's turned out just fine, no problems or warps that are visible.

So, BUILD AWAY!!!!!!

Patriot