Yes you can update using sn0wbreeze, sn0wbreeze always preserves the baseband, and now it also untether jailbreaks 5.1.1
There are problems with the old unlockable 1.59 BB and 5.x firmwares, mainly a single signal bar showing even when getting a full signal, when you install Ultrasn0w fixer 5.1.1 and then Ultrasn0w it should fix the stuck signal bar problem. Actually, until Ultrasn0w is updated to 1.2.6 to support 5.1.1 it will not fix the signal bar problem. It works on 5.0.1, but not 5.1 and 5.1.1
The problem is completely cosmetic, but can be annoying, I say update and if you can't fix it and it gets on your nerves, you can always downgrade back to 4.x using SHSH blobs.
If you have the apticket and blobs for 5.0.1, you can use Redsn0w to stitch a custom NO_BB 5.0.1 firmware that works with Ultrasn0w to fix the glitch.
Last edited by overdrive31; 06-02-2012 at 06:42 PM.