What is your experience with Muscial Concept Mods?

I recently purchased a Hafler 200 amp used and was thinking of having Musical Concepts do their Signature mod on the unit. However, it will be around $1K and I am concerned since I will not know how the modified unit will sound. Two questions: (1) What do members think of Musical Concepts Signature Hafler Mods and/or think of Musical Concepts mods? (2) Would I be better off buying a used SS or tube amp of of Audiogon for $1K. If so what would you recommend?

I have AR 2ax speakers, sound value pre-amp (older tube pre-amp), and rotel CD player with a modified Lite DAC (modified with black gate caps). I like to listen to jazz (Dave Koz, Chris Botti, KennyG, etc) or older rock (Eagles, Beatles, etc.).

Thanks for taking time to read my questions and provide feedback.

For the AR speakers I'm guessing the Hafler would be a better way to control and provide force than with a tube unit. My opinion would be to start with the CD player, if cd's and not vinyl are your source and try out different CD playters... 1k could get you a used Rega Saturn or other(s). I personally would explore very good cables, speaker and interconnect and power before plunking 1K down on an amp mod... also I happen to like AR's, I have a pair of AR 11's I'm playing right now but they are not super high resolution/detail/imaging/"space" champs like other more modern speakers and may not benefit from $1K mod. Just my 2cents.
What will the Hafler 200 sell for on Audiogon after it has the $1000 mod, and how long would it take to sell it? I suspect that if you sold the Hafler and added a thousand dollars, you might get an excellent recent production brand name amp, which you could easily resell when you moved on.
In this price range are many excellent choices, but my choice is a solid state Conrad/Johnson (2200, 2300, 2250, 2500). Because you have a tube preamp, the 100K input impedance of the CJ of might be helpful.
John is a pleasure to work with and has been around over 30 years, not a fly-by-night operation. His equipment and mods are know for being very musical. When his equipment does show up here on Audiogon it doesn't stay long.