Currently I'm really excited about the lower poly Level Of Detail V4 that is distributed with DAZ Studio. It takes all the V4 morphs / textures and comes in four different resolutions. The "problem" with it is that it works best with a subdivision surface-capable render engine, which Firefly isn't.

In Maya, the polygon reduction tool pretty much destroys your mesh, and overall is useless. I am mildly interested in the Okino poly reduction tool but it seems like overkill.

The best way to deal with this is model something low poly and smooth it / subdivide it. Doesn't work so well the other way.