Here's an alternative suggestion...
The M-Audio DMP3 : $159 (or less if you shop around)...
Then get the JJ Audio Mics mod for $100 http://www.gearslutz.com/board/new-p...-dmp3-mod.html
I just sent mine out. I'm looking forward to getting it back. This will give you two channels of very nice clean preamp for under $300.
And you're not crazy for looking at the Presonus TubePre. I have had mine for more than 5 years. It served me well as a vocal pre for a long time before I stepped into better stuff. These days I only use it as a bass/guitar DI though (works very well for this though).
The Grace 101/m101 is a very nice pre. I've gotten some sweet acoustic sounds out of that. If you take the time to mic it up right, you get a real nice result. And the tracks will be squeaky clean enough to make what you want out of it using EQ/compression/tape saturation plugins after the fact.
I've also had the RNP, and while it's a very nice sounding pre (just a hint of mojo/color), I feel that it's a tad overpriced for what it is. I'm sure a lot of folks will disagree with that, and that's fine. Just my opinion on it.
I'm really looking forward to seeing how close the DMP3 mod brings me into that Grace ballpark. They just started doing this mod, so I would think that in the next few weeks as people start getting their units back you'll be able to get a good amount of feedback on it.