Hi Stephen,
I have had problems with the 30 minute edit time before, so I changed the way I reply now. Anytime I think I am going to be making a reply that is more than two or three sentences, I write it in Notepad++ before I ever even open a editor window in Moodle.
I find that another advantage is that it also lets me scroll up and down to check out everyone's posts instead of only being able to see the one I'm replying to.