First: I dont have a C1000 yet, but a SL5500. So I dont know how comparable they are.
Well, on my SL5500 I use the (old) 64-0-CackoROM, means that the internal FlashROM has the base rom (only used to initialize), the RAM is completely free and all programs and data are on a ext2-SD-Card. Because the SL5500 saves all on /home they say "/home on SD".
Because of the lack of informations I've founded I dont know about the C1000. But I'd like to use a 1GB SD-Card (1 partition, ext2) for all installations and data. The internal 128MB FlashROM are used to store the ROM (32MB on 1.23 CackoROM) itself and the other 96MB of FlashROM are free for me, if I'm right. Well, I dont like to use the internal flash for installing programs and data. So can I have a "home on SD"-installation on the C1000 too? The free FlashROM could mounted to another mountpoint like /media/flash.