The pre's you've described...
Joe Meek, maybe Vintech Neve clone etc. are all quite colored. If you're looking for that kind of '70's Neve'ish kind of "Rolling Stones' acoustic sound (ala "Angie" etc) then definately go for one of them.
It really depends on your playing style.
If you are into more fingerstlye, folk or classical style playing then a more accurate sound may be something to consider. Bear in mind that your mic choice will make even more of a difference all things considered. And then we're talking stereo micing to boot!
Something I would definately consider is the Sytek MPX4.
http://www.sytek-audio-systems.com/mpx4a.html
While it lists at $1680, apparently Sytek have dropped the price considerably and they can be picked up close to $1000... AND they're a FOUR channel unit.
I used one about six months ago and was most impressed.
If you're looking for a lot of coloration then don't go for the Sytek.
In comparing an RNP to the Sytek I would say the RNP is 'kind of' similar but with a little more color. Remember that, per channel, the RNP and the Sytek are priced in the same ballpark... although the Sytek doesn't have a direct input.
Basically the MPX4 is very clear and focused without ever being thin, solid in the bottom end without ever being muddy and sounds amazing on acoustic guitars or pretty much most things. Would be excellent for recording acoustic instruments (classical etc) where you require a minimum of preamp coloration.
Really lets you hear your mic collection!