OK, I’m surprised. There is a new experimental release of the Imprudence Viewer out. You can get more information here: Imprudence Blog.
I removed the viewer some time ago. At one time it was my preferred viewer for building in-world. For even longer it was my viewer for OpenSim grids. But, it was slow adopting mesh and AFAIK still does not support mesh.
As far as I can tell this viewer is not Sever Side Appearance baking compatible. So, it is good for from 2 to 8 weeks, until the Lab rolls out SSA.