Motorola's Droid Bionic had always been much of a bastard child. it was announced, then retracted, then relaunched, only to be replaced a few months later by the RAZR line. And officially it's too old to receive Kitkat, i.e. Android 4.4. Final update it got was Jelly Bean... 4.1.2.
But don't let that discourage you. There are ways.
My phone was already tweaked to the max, with Cyanogen Mod 10 and all the CPU tweaks I can find. And with extended battery I last most of the day, but when CM10 is getting bogged down, a new start is needed, and thus entered... SlimKat, one of the handful KitKat ports for "Targa" (that's the internal name used by motorola).
My phone is already rooted, and safestraped with rom slots already setup. I did have to delete some stuff to make room for another ROM slot (each takes about 3.5GB), but that's not that difficult with apps like DiskUsage. Before that, I made sure I made a fresh nandroid backup of my latest CM10 setup (so if I have to go back I can)
Installing SlimKat turned out to take longer than it should due to my flaky USB port. I have a proper USB2 cable (AmazonBasics) but when I go USB mode and try to transfer 2 GB of stuff it just quit in the middle, the port goes bing-bong (disconnect and reconnect sound from Windows), and copy failed. I must have spend 4 hours trying different ports and different cables (3 each, in various combos) I ended up using my alternate transfer: WiFi Explorer.
After making sure all the MD5 matches, the ROM's flashed into the slot and boot commenced, and everything looks good. Had to set up Google again, but it's not a huge deal.
I wasted another 3 hours when I can't install any third party apps. Turns out my battery-bar overlay blocks installs. (WHA?!) Took me 3 hours to figure it out. Yeah.
Now it's working, and it'll take me another day or two to tweak it back to the way I had it.