Not sure about AmonRA but from what I have gathered in and about Clockwork Recovery, the partition option doesn't work all that well for most devices. It seems to bork the internal SD's that most phones have now days. Actually I have read quite a few articles that say it reformatted the internal SD (which is to be expected) but the for some reason it unmounted it from the device and then also destroyed the link that mounted the external_sd too. Makes you have to do unnecessary ADB work.
Here is an example. My other phone has a 16gb Internal_sd and I have a 32gb External_sd. Right off, I was told not to use the CWR partition option. The Internal_sd card was already partitioned at <2gb where all my apps and dalvik are stored leaving me 14gb of internal for music, pix and whatnot. I installed another kernel that has a lagfix with, guess what, EXT4. So now I have Fat, 2gb ext and my /system, /data and a few other partitions have been converted to EXT4.
MZ, if you want, I can upload the kernel and you and FJ can break it down to see just how it does convert the /system and /data to EXT4. Just let me know.
Edit: Had the kernel in here but Mchlbenner was right. Don't want someone bricking their phone b/c of me and flashing another kernel will definitely do it. MZ and FJ, if you want to take a look at the kernel and how it converts to ext4, just let me know.