For the locked 3g version, its not advicable to upgrade to 2.28 baseband for unlock. There are many error and problems reported everyday (in forum) after some of the users upgrade and unlock. Might be wise to wait for the next release of yellowsnow before moving to 2.28 baseband. (my opinion) Actually there are some custom-defined firmware of 2.2 with the previous baseband available. I would suggest to stay with 2.1 firmware's baseband till the better unlock patch is released (just my opinion).

those problems are unable to receive sms, could not retrieve call even tho signal is on, could not use edge, and miscellaneous.

Yea, inevitably there are some users which able to unlock without any difficulties so far, but theres some experiencing these annoying problems.

what im suggesting is a very conservative measurement in dealing with the 2.28 baseband.