Moving the CG ahead will reduce the angle of attack of the wing for a given amount of elevator travel, and thus reduce the tendency to snap out of loops. As CG is moved back, the elevator travel has to be reduced considerably. The problem could probably have been fixed by simply reducing the elevator travel.

I like to locate the CG as far aft as I can get away with. My only check for tailheavy or noseheavy CG is to trim the model to fly level upright, then roll it inverted. If it takes more than just a touch of down elevator to hold it level while inverted, it is noseheavy. The ideal is, of course, no down elevator, but this far aft CG may make the model a bit too "nervous" in pitch in bumpy air. If it climbs while inverted, it is tailheavy. Locating the CG at close to the aft limit for dynamic pitch stability makes for much easier vertical line holding, since almost no elevator input is required to hold vertical uplines or downlines.