Browsermark and Peacekeeper look like decent browser benches.

Also how about GUIMark3? http://www.craftymind.com/guimark3/ with some combination of the different tests perhaps.

GLBenchmark only appears to support iOS and Android and am not aware of any other multi-platform WP7 benchmark suites.

Agreed on the battery life opinion, I can just as easily make a charge last half a day or three days depending on how I use it and battery draining/benchmarks are hardly going to be standard across platforms.