Benefits: No SpeakerPhone Blast, improved memory, improved battery life, and better signal are the ones that I'm getting out of it (I was on the same OS as you)
Just follow the instructions to do a clean wipe and fresh install and you should be fine.
The latest os posted on top of thid forum is the latest known to exist. It may not be supported by your carrier. Most of these new versions are usually only minor bug fixes and stuff done that the average user won't even notice a difference with.
Posted from my CrackBerry at wapforums.crackberry.com
Con to doing the upgrade, voiding mfg warranty if Verizon knows you had a non authorized os on there.
Do you have any issues with 4.5.0.77? If not I wouldn't upgrade. Don't try and fix a problem that doesn't exist. Usually leads to more trouble then its worth.
That's my $.02 atleast
Posted from my CrackBerry at wapforums.crackberry.com