I`ll give everyone a little tip on this exercise that most people Fail to realize,
Stick your arm out to your side, now bend your wrist as far and as hard as you can.
Not only will you get more benefit for your chest due the synergy of the muscles from the forearm up, you will also be able to become a better "lever" to move the weight and you will not have to worry about balance as much. This may not benefit short armed people too much, but long-armed it should dramatically make a difference.
First of all, dumbell flyes? WTF? Everyone has a certain bodypart that is stronger, but I s'pose if he has accepted then fair enough.
Secondly, heavy db flyes are prone to injury anyway, but doing them with the elbows straight, and the wrists curled in is almost suicide. Some people can go really low on them, but for most people when you go past parallel to the floor, it's no longer a case of how strong your chest is, its how strong your tendons are, which isn't really what you guys are competing about.
Adonis, why not back up your original challenge and post a vid of a PL movement. If you can't lift heavy due to low bodyweight or whatever, then you shouldn't have made the challenge in the first place.