[Galaxy S I9000 Android Development] g00ndu:
I have just flashed to JPC and restored my apps. Rooting procedure is exactly the same, except of course the kernel is a JPC.

There are some differences between the 2 leaked firmwares.

The biggest difference between the 2 is that ZSJP2 has an additional Dock Settings in the Settings menu. XXJPC does not have. This means that Samsung will be launching a docking station soon, probably in the Asian market first.

USB settings is now located in the wifi settings tab for XXJPC while it is still located in the About Phone tab, like all previous eclair firmwares.

In the Settings button (bottom left), once you pressed it there are only 5 options available for ZSJP2 but 6 options for XXJPC. The missing option is the Edit (homescreen pages). It is logical not to have this Edit option since you can now do pinch zooming to select or remove one of the homescreen.

Another significant difference is the removal of widgets in your homescreen. For ZSJP2, when you long press the widget, you have the option of either to remove the widget OR you can uninstall the app altogether. In XXJPC, you only have the option to remove the widget, something that is similar to the eclair rom.

One more difference is the apps pages, ZSJP2 does not give you an option to list the apps, only edit is allowed. XXJPC has both edit and list option, similar to the eclair firmwares.

Regarding about numbers, linpack for both is similar. For quadrant without lagfix, XXJPC has a higher number, which is 1045 while ZSJP2 score is 945. When I applied RyanZA lagfix, both scores were similar, in the range of 1700+~1900+.

ZSJP2 suffers from boot freeze, and it occurs at random. It can be when you apply quick boot, or power on, or when you are in the recovery going for a reboot. So far, XXJPC does not have this problem. Note that I do a factory reset, wipe cache and format internal sdcard.

Bootup time for ZSJP2 is slightly slower, and can be felt between these 2 roms. There is also a bug in ZSJP2 is that when an app stops working and a popup says that force closes, once you clear that popup, the whole app actually disappear. Happened to me twice when I'm on ZSJP2.

In terms of responsiveness, I would rate XXJPC to be better than ZSJP2 for everyday usage. In my own opinion, the user experience is better for XXJPC.

Downloading of apps from market is always a challenge, and occasionally it suffers from a lag. Both firmwares are about the same. Of course the first download will always be the fastest.

In terms of battery drainage, I have not really tested out which one is better. But both fare badly when you compare with the eclair rom. Not sure why, but believe that this issue will be ironed out in the official release.

Overall conclusion, based on my personal user experience it seems that XXJPC is a better firmware than ZSJP2. Having said that, it is possible that my ZSJP2 flash might have gone bad, but unlikely to be the case.

Oh, last but not least, when I checked the ProductCode for JP2, it is still HKAXEU, same as the eclair 2.1. But the productcode for JPC has changed to HKAKOR, this is something which has also been mentioned many times in the xda-forum.

Also if you hook your phone to the pc, instead of 2 drives, you will see an additional drive, which is a CD drive. Again not sure why this is so, maybe has to do with the 2 different kernel.

All in, that is my short and brief review between these two 2.2 firmwares.