Board Thread:General Discussion/@comment-4972407-20151005050700/@comment-25751901-20151006062037

The different is:

GUR without maxing can 1-skill kill almost everything. But cannot 1 tap kill another GUR.

Max GUR is almost immortal when finght unmaxed HSR.

So, I think the decision depends on how your alliance is. If you always face those top-tier alliance, I think maxing GUR is a must. If you only face middle, low-tier alliance, not to bother maxing. :)