If the current baseband works with the gevey sim, just make a custom no baseband upgrade using redsn0w and then you can update without worry using that custom ipsw. If you're not upgrading to 6.1.3, you need to also stitch the SHSH blobs with the custom ipsw
About factory unlock, I'm unsure about that
Thanks Darrick. I have a few follow up queries:
1. I tried d/l redsnow but apparently there are too many versions available. Should I just "d/l redsn0w 0.9.15b3 (Windows) NEW" or do I need to work with any other version?
2. Are you suggesting I should go for 6.1.3? I am not sure what that stitch thing is all about as I am not even that tech savvy. So whatever version of iOS is easier to update w/o any risks, I'll be happy to upgrade to the one. So please advise accordingly.
3. Also, are there risks involved like bricking the iphone etc. while doing such upgrade? If so, what is the % probability?