There is no such thing as a "best choice" airplane when it comes to acro competition - especially at the lower levels. The RV has just as much chance at winning Sportsman as an Extra. It may be hard for those not involved in this sport to understand this. Your air racing analogy does not relate at all.
The contest results speak for themselves. I won't bother going to look for them again. Looking forward to seeing Ron and his -8 at our contests again.
And I don't think we have a semantics issue. Let me once again be clear that by "competition acro", I mean IAC contests and their associated style of flying. I'm not aware of any other kinds of contests, or competitions involving aerobatics in this country. Plenty of you are qualified to comment about basic aerobatics in general, but on the subject of competition acro, let's keep it specific so we don't have those not involved in the sport negatively influencing others on what it's about.
Sandifer is correct. I've flown IAC competitive aerobatics up through the Advanced level, owned a Pitts S-2B, instructed in everything from Extras, Decathlons, etc. to RVs. I'm also a National level judge and have given seminars, written articles, and served as an IAC chapter board member and contest director.
Roll rate and vertical line length have no bearing on judging criteria whatsoever. I've seen a guy in a stock W-670 powered Stearman beat one in an Extra 300S flying Sportsman. When I was flying Intermediate in the Pitts, I routinely got schooled by a pilot in a Great Lakes.
While I'm not crazy about snap rolling RVs, the aerobatic RV models are more than capable of flying with and beating anyone flying anything out there in Primary, Sportsman, and Intermediate. Advanced and Unlimited would probably be beyond the capabilities of the aircraft, but then my Pitts S-2B is also becoming marginal for Advanced, especially at places where the density altitude is higher. You can make it work, but it's a lot of... well, work.
In competition, success is determined by the capabilities and execution demonstrated by the pilot, not the aircraft.
RVs are a little different from most of the other airplanes flown in competition in the sense that they are very low on drag and build speed relatively quickly when pointed downhill. But as long as that factor is known and planned for, I think the RV series is an excellent airplane for both competition and non-competitive aerobatics. I love the way the efficient airframe preserves energy between figures.
P.S. The fact that it does build up speed quickly when descending is yet another excellent argument for pursuing quality instruction in aerobatics.
--Ron