What is the source for your picture? Cable/Sat, or OTA?
Stuttering and freezing is usually the digital verson of static. If the source picture is your problem, the firmware will probably not improve the picture. Although, it won't hurt the unit either, so if you're inclined to try it, go for it.
However, I think the underlying source is a weak signal on the television. Since HD takes more bandwidth to broadcast and receive, any "static" or interruption of that digital feed will cause the stuttering and freezing.
I am having a problem on several (but not all) HD channels. The picture stutters. Basically, it freezes for a half second or so, then catches up with the broadcast. It's unwatchable. Would a firmware upgrade help this? It's version 1010.2 and the current version seems to be 1013.3