Question Updating from samsung 4.1.2 to slimbean 4.2.2

In the past i tried to update from 4.1.2 to 4.3 and my imei has changed to 0049
I understan its related to the new modem.

Now i have a brand new s3 and i want to go back to slimbean 4.2.2
Is it dangerous to update from 4.1.2 to SB 4.2.2 ?
Is there any chance that my imei will change again or its using the old modem?

Thanks.