I'm personally not a huge fan of the UA 710. For a very similar price the UA 610 is better sounding. In the same vein though, similar price I think something like an Avalon M5 beats out both - but that's just preference.
I don't think the Pro VLA II is going to give you anything that a software compressor won't get you. It's also a 2 channel, which you don't typically need for vocals. Lindell Audio makes an 1176 clone for roughly the same price that isn't bad - so if I were dead set on an outboard compressor in that price range that's not a bad place to start.
