Very recently whenever I'm on my iPad and try to quote something, the whirlygig gets going and never stops. I can reply, just not quote.
Yeah, I asked because it does a similar loading dance, though I haven't experienced any hanging. If you haven't yet, I'd give it a whirl. Not just because of the issue you posted, but because it's a really nice way to browse (supported) forums when mobile.
Okay, I found it worked on one pad but not another. So I tracked down two more. Here's the results: iPad 1 - worked iPad 2 - failed iPad 3 #1 - worked iPad 3 #2 - failed Go figure.
Okay, rebooting the iPad seems to clear the problem. Go figure. It's either random or there's some weird Safari glitch that somehow only affects the Reply With Quote button.