Flying Arm bar is an awesome move, probably the best combination of skill and athleticism.  The difference between doing it in practice and actually doing it, is when you actually go for it, you land hard on you head.  In practice your partner holds a lot of your weight.  Every time I've pulled this move I've ended up rocked!  But I am usually able to hold on to it.  It would be well worth it if you landed one in competition.