If I had to choose the sound character of the ACE - I would choose Warm over lean, so I could see how Chadnliz might think that is sounds "warm, mushy and pretty boring". I am guessing that Chadnliz probably likes a more sparkley and lean sound. I would never say that it sounds mushy and boring. Warm...yes, probably more on the warm side than the cool side. That's why I was so surprised by Audiofiel's statement that the cartridge was lean and harsh.
Be careful what you match it with. I will say that I pared my ACE with a warm "Polite" integrated (Magnum IA170) and it does make the sound to warm and fuzzy for my tastes. I am in the process of upgrading everything and I will definitely be looking for a new amplifier.
As you can see, everyone has an opinion. A lot depends on how the cartridge is set up. A lot has to do with what components it is mated with. Anyway, good luck with your venture and let us know what you decide.