iPhone 4 ;4.2.1;bb 03.10.01 Is it safe to upgrade to ios 5?

[medxx]

iPhone 4 ;4.2.1; bb 03.10.01
I want to upgrade to ios 5.0 but not sure if after the upgrade am I able to JB and unlock my phone or not. I have windows seven so redsnow won't preserve the bb for me !
Currently I am unlocked using gevey sim ! So if I upgrade the iOS will the gevey work!
Ease tell me what wud be the best thing to do
Plus is there a chance that the bb upgrade done by ios 5 will be unlocked in the near future

Is it safe to upgrade to ios 5?

[i.Annie]

I've researched that it should be fine.

Just preserve your baseband by using a custom firmware to restore to iOS 5.

If you google "Gevey iOS 5" you should be able to find some guides on how to get where you want to be.