The two Phoenix that I saw fly both flew very well. One was being flown by a 6 year old. One was mine.

Tail heavy airplanes give the elevator all the power it'll ever have. Most people diagnose tail heavy when they experience an elevator that feels too quick. If your elevator feels too quick, first thing to do is dial in some exponential. Second thing to do is move the elevator horn connection to the outer holes in that horn. It's actually better to move the pushrod connections on the elevator servo in to the inner holes in the servo arm. THEN check out the CG location in flight.

There are a couple of different ways to check the CG location of an airplane that work good. They are done while flying, so obviously you preceed them by verifying on the ground that the CG is where the mfg suggests before you take off. The other thing you do before flying is check to see that your elevator throw is roughly what the mfg suggests. You've done those prep things, right?

A powerful elevator isn't a bad thing (unless the CG is too far back). It's dead simple to adjust the servo-to-elevator connections and you'll have a better flying airplane than it'd be noseheavy. But check first to see if it's tailheavy.

Fly the airplane upright and inverted. Top speed works. Slow is a little risky. If the airplane tends to climb when inverted or you have to hold "up" to keep it level when it's inverted, you're using the elevator to carry the tailheavy CG. You can also do a dive test that works about the same way.

Trim the airplane for level flight at about half throttle. Use the TX trim to get a hands-off level flight at that speed. Do this at a decent altitude. Once you've got it flying level on it's own at half throttle, point the nose down between 45 and 60 degrees and let go. It will naturally pick up speed. As it does, the trim you set for half throttle will become more effective. If that trim pushes the nose down and the dive gets steeper, you've got a tail heavy airplane. The trim was having to carry that "tail heavy" CG in level flight at that slower speed, and now that the airplane is going faster (without help from the prop) the trim is doing even more trimming and that's tucking the nose under. If the nose comes up in that dive, you've got a noseheavy airplane.