Well, the nice thing about the RNP is that you'd get TWO channels for under five hundred bucks.
Then, if you get the RNC to go with it, you have two channels of pre's and compressors. So you could record stereo, yo?
I have a focusrite Green series
voicebox, it's nice. pre, comp, eq, all in one unit. It's a step up from the platinum range. I paid $450 for it, I think, on ebay. I like it quite a bit, especially for vocals and acoustic guitar.
I also have a Meek VC1Q, which I like a lot, but it's a thicker sounding unit, which some people don't like. I like it BECAUSE of that on a lot of things-and it's super nice on some vocals, not so nice on others. Kills as a bass DI, electric guitar mic pre, even on some snare drums. It has a pre, comp, eq, etc. I paid $400 for it on ebay.
But overall, it depends on what works with the particular vocals you're going to be recording-and whether the extra flexibility of, say, a two channel preamp would be useful or not. I've not really heard a bad thing about the Grace units, they'd certainly be a good choice.
Hope that helps,
Chris