I wonder how many occurances of tail separations by type have occurred. My memory isn't what it used to be but I suspect the -3,-4,-6, -9, and -10 do not have the same frequency.
I've kept track of structures-related accidents in RVs in general, but my focus is obviously on the -7.
There have been two other RV-7/7A tail separation accidents in recent memory that appear to be similar to this one. One was a Canadian RV-7A, C-GNDY, which was
investigated by the Canadian Transportation Safety Board. A later one was an RV-7A, N174BK, in New Jersey, which was
investigated by the NTSB. Both of those accidents had much more data available from which to draw a conclusion, so in this case I think the NTSB did the best they could with what they had.
At the risk of being accused of speculation by a mod, all three of these accidents were "big tail" RV-7As, i.e., with RV-9 rudders, and according to the accident reports, were estimated to be well above Vne (20-35 kts) when structural failure occurred. The RV-7's rear fuselage and stabilizer structure is very similar to the RV-8, and given the relatively greater use of the -8 for aerobatics, and the probability that some have been past Vne, should we expect to have seen similar accidents in the -8? Of course, that question leave a lot of factors out like build quality, pilot training, usage spectrum, sample size, etc.
I'm forced to wonder if the combination of the -7 VS and -9 rudder may be less robust than with the original -7/ current -8 rudder, but the bottom line is still to fly your airplane inside the design speed/weight/CG envelope.
Dave