We seem to talking about 2 things here, V-tails and anhedral stabs, so I'll comment on both from the standpoint of an aerobatic plane.

V-Tails: I have flown several and built a few. In my opinion, they are fun for a while, but not very good from an aerobatic standpoint. You get a lot of unwanted yaw & roll from them. In an acro plane you want to decouple all the axes so you can use rudder, elevator and aileron independently. With a V-tail, this is impossible. When you are in a bank and use elevator, one half of the tail is pulling the wrong direction. V-tail planes also tend to barrel roll. I'm not a pattern flier, but I do like my fun fly planes to fly somewhat correctly.

I once built a Duraplane with reduced incidence (stock, it has a lot), downward tip plates to reduce effective dihedral and a V-tail. Used a Fox .50 I had for power. No gear-hand launched. Talk about a graphic demonstration of rear fuselage torsion from a V-tail. I could snap a couple of times and release and watch the tail rock back and forth. The same with full power spins.

Also tried a V-tail on a PVC fuselage like a SPAD. OS .46 powered. With the lower half of the PVC fuselage cutaway back past the wing to save weight, I also got the wiggling of the tail after snaps. I made another PVC fuselage without the cutaway and screwed the V-tail to it. It reduced the wiggle, but not completely. I finally went to a conventional tail which cured the problem.

The PVC fuselage, Coroplast wing planes are easy to cut-and-try some of these ideas if you are interested in seeing for yourself.

Anhedral Stabs: The first pattern plane with an anhedral stab, as I recall, was Hanno Prettner's Curare. I recall reading that he did it to lower the stab and increase the side area. The F-4 Phantom was a first line fighter in those days (I flew it in Vietnam, by the way) and the anhedral stab on it may have had some influence. I flew a Curare in pattern for a while many years ago so don't put too much credence in the fact that anhedral is supposed ot be destabilizing. The Curare flew great, as did everything else Prettner designed.

One of the reasons for lowering or raising the stab is to correct a knife edge pitch with rudder. Remember, we want pure yaw with rudder. Anhedral would have the effect of lowering the stab.

Joe Bridi had a slight amount of anhedral in his UFO, about an inch, I think, but I feel this was for looks and not for any engineering reason.

I had a high performance fun fly type plane back in 1976-77 time frame when I first saw the Curare. To try anhedral, I sawed the stab on either side and glassed it back on with about 3 inched anhedral. I didn't notice much, if any, difference. Later on I bought the Curare kit and flew a little pattern.

As I mentioned, the 2 1/2 square drail pipe PVC fuselage planes are easy to modify, especially with Coroplast tails. You could use any wing and screw on conventional tail, V-tail, T-tail and anhedral stab very easily. You could also put the stab in the top, bottom and middle of the fuselage. I've had a bunch of those planes, both with Coroplast wings and wings from crashed planes or old junkers. They are fun to play with and they can give you a lot of insight into whether the theory is just a lot of BS or not.