A few quick comments - you can take them or leave them, but I think they're pretty much going to directly relate to your dilemma:

1. Power to weight is nothing if you're killing your wingloading. High wingloading means a stall happy plane, that is not going to fly 3D well.

2. The Phoenix Extra is not a 3D machine. There are very few 40-46 size planes that are going to perform like a 25 - 40% anything. That's why most small 3d planes are lightly built, and have nice big thick wings like a Funtana/Twist/Ucan do/Mojo/Harrier etc - then, that makes them less precise for IMAC type flying.

3. 3D flight is a whole lot more than just hovering an airplane.

Now back to your questions:

Well, you're talking about a 10oz difference from the LA46 to a 61Fx, or either of the Tower motors. It's your choice - the problem here is you have a plane with very little wingarea, but it is already over the 6lb mark, and Extras like to tipstall to begin with. You might be better off looking at something like a Saito 72, or OS Surpass 70. If you have the $$$ and didn't want to add any weight (which is a good thing) - Look at the OS 50SX - lots of power there, real screamer of an engine. It weighs barely more than the 46 you have now.

When you look at it this way - that 40% Edge in your gallery, probably requires at least 8 servos similar to the JR 8611, or the Hitec HS-5955 - @ $114 each you're talking a minimum of $900 in servos alone - another $300-500 on battery system, wiring, Receivers, Control horns and linkages, and $1600-2000 for something like a DA150 or 3W 160 - look at how much cost you have there. Splitting hairs over powerplants for a $110 ARF shouldn't be a consideration.

As for the question about the rolling - Check the wing for warps - hold it up and look down the leading and trailing edges, are either bowed or warped significantly? Check for twists from root to tip - if none are present, then the wings are fine. Do your control surfaces move freely? When you feed in left and right on your transmitter do the ailerons muve equally in each direction? Lateral balance is never going to keep a plane from simply performing a roll, unless you're talking abot a ton of difference, like an entire wing panel missing, or your buddies played a trick and poured plaster down in your wing while you weren't looking.

Did the plane want to keep rolling the other direction on it's own, or did it trim out pretty much normal for hands off straight and level? If so - I'm guessing you might have lost a servo in flight, forgot to plug one up, or something is keeping an aileron from deflecting properly.

I've built combat planes out of gutterpipe and hand cut foam wings that were plenty maneuverable - if you're experienced with that 27% Extra 260, and 40% Edge in your gallery - assembled them yourself, and they are set up and fly perfectly - then figuring out issues with a 46 size ARF that was assembled per the instructions, shouldn't be that big of a deal.