May I suggest upping the limit of 30 characters to 70
+1
This should be the default -- or no truncation at all. User-generated subjects are already limited to 50 characters by default. In addition, UBBT 7.5.8 raises duplicate content flags by also inserting four more characters to the URL, as "Re:_", to direct links to individual posts.
If it's obvious, I don't see it. Is there any reason for new SEO URLs to have truncated titles, if the title is intended to be used for SEO while still remaining user-readable... and it's already being limited to 50 characters elsewhere?