Can I use the SD/MMC with a SCC cart on the second slot? Or would I need to adapt the .ROMS to look for the SCC on a different slot?
That's what I like to know too.
Can you use this SD device together with a SCC cart in the other slot ?
In other words : is it possible to load a disk version of a SCC game with this device while using a SCC cart in the other slot to have SCC sound 
If this is possible, you can sign me up for one 
Excellent! I'd be very interested in one too, even though I don't need it that much ATM. Erikie, before ordering up a batch of these PCB's: could you try and find out if it's possible to have these made with gold(plated) contacts? It may be much more difficult to get / expensive, but if possible: might be worth it. Tinned contacts are fine when all shiny and new, but when corroded enough (doesn't take long) you *will* appreciate gold contacts. Other things (like case, LED's, software etc.) could be done by end-users, but to put gold contacts on a PCB is not a DIY option 
Anyway, it's about time Sunrise's CF-ATA interface got some competition. It's a nice piece of kit, but a) it's expensive, b) rather big cartridge, c) SD cards are more convenient these days, and -most importantly- d) damn near impossible to obtain one.
gold plated contacts are no issue. My v1.0 also had them 
I will ask again for those on this batch. It is indeed a bit more expensive but not too much.
And SD can be used together with scc rom in other slot as long as the game has scc detection or manual selection option.
I will try to play a dsk version of an scc rom and let you know if it works. Need to find one though as I only use roms in flash rom
it certainly works best to have an scc flash device at hand for roms. I have several (ese-scc and megaflashrom)
The good thing of the SD device is that you can use a fat32 2gb card to transport files from PC to MSX
hmm, makes me thinking if it would be possible to have 2 flash roms on this device.
and a switch so you can see it as 1 big flash rom of 1Mbyte so you can flash the 2nd 512K
and then switch off the msx and flip a switch on the device so only the 2nd flash device is used for playing games
there is more than enough room in the cpld to built in extra logic for mapping but I need to experiment with 2 flash roms to make something work like this. Anyone have ideas how to add a second flash rom so we can flash that without problems?