You can flash the kernel only on any froyo 2.2 and you will get the same result as with this new ROM, and you can keep your existing CSC, Modem and ROM. You will get the same speed and 339Mb of RAM, quadrant score for those interested is 1237. It's the kernel that is very good, the ROM itself in my opinion is not different than any other froyo 2.2. I have tested this on European JPA so I'm almost certain that it will work on JPM. Here is the kernel for those that want to try flashing the kernel alone and see the result:
http://www.multiupload.com/BK1WGZP505 Flash as PDA in Odin, no pit and no repartition, or extract if you want to flash using Heimdall, boot into recovery and do only a cache wipe, you don't need to do a full factory reset. You can root using Super one click 1.5.5.
