JFFS2 and large flash

I recently tried using JFFS2 on a large NAND flash partition (512MiB) with 
less than inspiring results. Turning on the summary option allows the 
partition to be mounted in under 10 seconds rather than 2 minutes, which 
is good, only I found that if I actually did any work on the filesystem 
and rebooted, the garbage collection thread would eat 100% CPU and all I/O 
to the flash would block. This got progressively worse the more work I 
did, to the point where the system became unusable after writing only a 
couple of hundred MiB of data.

Clearly something better is needed. I've used YAFFS (v1) on a 192MiB NAND 
flash partition, and it's worked extremely well -- I haven't noticed any 
data loss and we literally pull the power on our devices to switch them 
off with no noticed corruption. I'm hoping that YAFFS (v2) will sit nicely 
on my 512MiB partition.