When you say it wouldn't let you hang, could you elaborate? Would it not stall so you could enter a hang, or would it fall out of a hang, or what exactly?

I have a couple of thoughts, based on an assortment of personal experiences. You might be facing two different phenomena at once, and neither one may have to do with reverse rotation. One may be the different gyroscopic affects of using a heavier plastic prop vs. a lighter wooden prop. This could give you some stability issues. It might also be that the E prop is so much more efficient (you did say it was faster) that the airplane just won't stop flying. I believe on electrics that the throttle doesn't go all the way down to zero, so maybe minimum rpm is still too much with this prop. Depending on your level of curiosity, you could try wood Zinger 9x6 props in both rotations, heavy APC 9x6 nitro props in both directions, and of course the normal rotation 9x6E prop. Then, by noting how the different props responded, possibly reach a more definitive conclusion. Or, if that's too much work, you could try a Master Airscrew 9x6 electric prop. It should be faster than the TF wood nitro prop since it's designed for electric, but the blade is fairly narrow like the TF so the low speed handling may be similar.

Or I could be wrong...