Unfortunately I don't have one of those and AFAIK you're the first to try so it's completely untested so far :-( Since you have one, could you post the output of df? I'm particularly interested in how much space is available on the initfs partition. Understood. Please don't feel under any obligation to try it, but if you decide to do so see this post for how to roll back to the official version if anything goes wrong (and make sure you have a fresh backup of course).
Nokia-N810-WiMAX-43-7:~# df Filesystem 1k-blocks Used Ava ilable Use% Mounted on /dev/mtdblock4 4096 3472 624 85% /mnt/initfs none 512 144 368 28% /mnt/initfs/tmp /dev/mtdblock4 255488 206628 48860 81% / none 512 144 368 28% /tmp none 1024 60 964 6% /dev tmpfs 1024 0 1024 0% /dev/shm /dev/mmcblk1p1 3923968 617408 3 306560 16% /media/mmc1 /dev/mmcblk0p1 1922972 117892 1 805080 6% /media/mmc2 Nokia-N810-WiMAX-43-7:~#