The .25LA is good with a 9-4 APC (and a reasonable load for a new engine). My Skyray likes a 9-4 Graupner a bit better. A 10-4 Top Flite Power Point (admittedly thinned some) shows promise. As the engine gets more time on it, I'm going to try 10-3 and 10-4 APC and Graupners, and I have a 10-4 Taipan to try.
The Super Clown is a fair sized airplane, so I wouldn't expect an 8" prop to work very well. Dan McEntee reported the .25LA works well with a 10-4 APC on his Primary Force....in St. Louis. I'd expect it to work better yet, here in Seattle, with cooler temps and lower humidity. I'm also going to look on the APC website and see if there's anything in the 9.5 x 4 range. They have lots of stuff never seen in the LHS.
Never stop testing new props. Find one that works, but keep looking for a better one. The prop that flies the model best may well make it last longer.
Steve