McCormack SMC Audio upgrades: how good are they?

Does anyone know, or can tell me, how good the McCormack stuff sounds when upgraded by SMC audio? I was trying to determine whether to keep my DNA-125 Gold revision, or to go to a higher-end SS or tube amp. Budget would be $3k for an amp, or $4k for an integrated, both used. Has anyone had or heard a DNA-125 or 225 Gold and compared it to other amps? The stock amps sound a lot worse than the Gold revision (it costs $1700 for the upgrades), and I have never seen one used on here, which probably tells me something right there. Still.....

I can't listen to any high-end pieces around here, and have the upgrade bug again, but it may be unjustified at this point. Are there better units available at that price? Preamp TBD as well, but looking to spend $2k. Currently using a Dehavilland in my system. The problem with audio is that it seems that there is always something a little better lurking around the corner....