I had one commenter whose been quite fun to dialog with complain about the commenting problems that seem to permeate Blogger.
I actually have no control over the commenting issues, at least none that I know of.
When I get the too many character issue (over 4,096 or something), I just cut and paste into multiple posts. I always type my posts in Notepad or Word and then cut and paste.
The request URI doesn't keep it from posting, just hit back on your browser and it should be there; at least it usually is for me. It's annoying, but it is possible to work around.
Other than that, I'm certainly open to suggestions. Blogger's been doing weird stuff for a few months. I don't know why. I just think the hassle of switching providers would be too much, and I like the Google interconnection.