I think I'll be OK to install this new update, assuming it is verified to be legit from Verizon. But it's unexpected so I wanted to make sure.
My wife got the 5.5.893 update pushed to her Bionic, but I got tired of waiting so I downloaded the OTA file that someone had copied off their phone. After installing it manually, I compared the version numbers of all the components to my wife's and they all matched, so pretty sure I got the exact same 5.5.893 update as if it had been pushed. I was not rooted at that time.
After updating I rooted using the one-click root for PC that can be found on the forums. I installed the Bionic Recovery Bootstrap app and used the Recovery to make a nandroid backup. Then I froze about 35 bloatware apps using Titanium Backup, installed a new default font (roboto) with Font Installer, and changed the boot animation with Root Explorer. Haven't installed any ROMs or anything like that.
When I heard about this new 5.9.901 update, I applied the Forever Root that involves editing the mount_ext3.sh file in the system/bin folder with Root Explorer.
Now I'm thinking I should be able to install this new 5.9.901 update manually, assuming it turns out to be official, after defrosting all the bloatware first. Hopefully I will keep root due to the Forever Root exploit and then be able to re-freeze the bloatware. Does that sound right or am I missing anything? Can't afford to brick this thing.
Oh almost forgot -- how do I get into the default recovery now, instead of the ClockworkMod recovery that Bionic Recovery Bootstrap installed? Assuming I'd want to install the 5.9.901 update using the default recovery, that is. Or does it matter if I install it using ClockworkMod recovery instead? They basically do the same thing, right?