Only stock recovery can flash the radio. If your radio and rom are mismatched (ZVD / ZVH) you will likely have problems with data. Stock ZVH rom is not rootable.was wondering why everyone thinks this is a big deal..... yesterday night i was messing around with my phone because i really wanted to go back to stock and i just flashed the update.zip zvd file to my phone... was nervous because i was rooted and running drew's cm7 rom.... so it flashed successfully..... so went ahead and flashed the zvh update.zip file and that to flashed successfully.... dont kno yu have to go through all them steps just to go back to stock recovery
As long as you understand all that, there is no big deal.