I am another with positive experience with the ACE.
I purchased a nearly mint one (no box) and it has been very reliable and definitely accurate enough to be a good "can chaser" The other is another nearly mint one with box and papers. I have not shot that one....yet. Both are 1978 guns.
Anyhow, the one I shoot has been a blast. I usually don't shoot more than 100 rounds in a session but it never slows down on Mini Mags. I really like it.
Where they screwed up with the floating chamber was to not do it like Remington did with the 550 series. On a 550 (IF I recall correctly) when shooting long or long rifle (same case length) the case actually bridges the gap between the floating chamber and the fixed chamber. So the floating chamber doesn't recoil until the brass de-obturates. However, when shooting shorts, the case is only maintained by the floating chamber causing it to "boost" backward during the firing sequence, thereby cycling the gun. In this instance, the gases flow around the floating chamber which gets the gun dirtier more quickly than when shooting long or long rifle cases.
Colt's floating chamber however, is the length of the 22 lr cartridge case so, when the gun is fired, the gases can immediately flow around the floating chamber which dirties up the works quickly, like a 550 shooting shorts.
If Colt had used a shorter floating chamber sort of like a "delayed blow back" system where the cartridge case bridges the gap between a rear and front portion of the chamber, I think this would have made for an ACE that could shoot for a lot longer of an interval between cleanings by the virtue of holding the chamber closed until the pressure drops when the brass de-obturates. This means the action doesn't move until a larger volume of powder is burned thereby decreasing the amount of unburnt powder and crud in the chamber.
Strictly theory on my part.
Here is my "shooter" ACE in keeping with the spirit of the thread.