There really aren't any out there. At least I'm not aware of any?

.stl files don't contain any arcs, just flat triangular faces.

I've cut quite a few 3D ,stl models, and have never seen any faceted areas on my carvings. Have you tried increasing the .stl resolution when exporting from your CAD program?

As for file size, I don't really see an issue there. The largest g-code files you'd probably see are tiny by today's standards, and shouldn't really cause any issues.