I think "analog flavor" in an ADC is pure hype, it's stated to cover up flaws like jitter and lack of headroom (I'm not talking about DSP like on the HEDD). The Crane Song HEDD is a wonderful piece with the ability to put in "tape" and "tube" flavor in addition to being able to turn it off when those are not applicable. Benchmark makes wonderful ADC's, and are soon coming out with a slightly low cost unit with mic preamps installed. I believe a unit with no mic preamps is to follow in the sometime future. Mytek is also coming out with a 2 channel , ADC only unit in the next 4-6 weeks. All of the companies that make these units have an eye towards a 'hi-fidelity' basically pristine kind of sound (with minor tonal variations between each, just like Grace and Millennia preamps are both different, but both are still "clean") what you put in is what you get out, as far as an ADC can allow anyway in 2003. Here are a few links to get you started:
http://www.benchmarkmedia.com/news/awards.asp http://www.mytekdigital.com/kramer.htm http://jdvservices.com/stone/press.html#cranesong
Based on the excellent past track records of these companies, I don't think that you can't lose with any of these. Remember, 2/3 of these specific products have not been released yet so they are still subject to scrutinization. However, I doubt that Mercedes or Rolls Royce will be putting out a piece of trash onto the market, nor will CS, Mytek or Cranesong (as some might have you believe just for the sake of arguement). And if you find you don't like them there is always room to try something else instead. From my experience, when one gets to a certain high level of gear it comes down to functionality and features in addition to price factors. At least you have indicated that you can hear the difference and realize that what you currently have could use improvement, this is a excellent first step in the right direction.