Holy crap man, you managed to do loops out of idle up mode? DO IT DO IT!!! Idle up is not all that scary. Just get used to putting it in idle up on the ground, and taking off/landing in idle up. Put fuses on your motors, and you 'll be fine.
I say this because I almost always fly in idle up now, and every attempt at a loop has ended in a crash.
My best stunt so far is deep stall turns, but can't get it past sideways without going into dork mode.
I will still argue it is **completely** possible to loop with flat bottom blades, because I've seen it done. Especially if you're tuned with more negatinve pitch than positive. It just means you have more lift right-side up.