I don't know if you can give me some general pointers here but I've taken the plunge and ordered an SL-C3000, haven't decided what to do with the SL-C860 yet.
I was thinking of perhaps adapting as much as possible of the 1.22a ROM for this unit and as such I have the following in mind... if it turns out OK and you want to host it to keep tabs on Cacko distribution then that's cool by me.
i. Examine Cacko patch set and merge appropriate patches set to SL-C3000 Kernel (2.4.20 based of course - omitting all ATI stuff etc.).
ii. Diff out the rest of the changes from the original Sharp distro to find the Cacko changes. - I would like to confirm the base Sharp ROM that you used.. 1.10, 1.20 or 1.40 ?
iii. Ask your advice on more custom stuff. I anticipate that things like Kino/Mplayer won't run out of the box so I may initially just leave them out but in the longer term it may be good to try a Kino/Mplayer combo without the ATI acceleration. <UPDATE>Just seen your SL-C3000 support bits on the Kino page </UPDATE>
What do you think? BTW have you had a chance to play with one of these units yet?