(full disclosure: I am not a cloud9 employee but I work closely with them on some projects)
The SuperIDE does indeed do more than the Drive Pak. I am constantly surprised by all the stories of people waiting and waiting for a DrivePak and not getting one. I'm no longer surprised they are getting ripped off, sadly that seems to have become par for the course. What surprises me is that they order one in the first place when a clearly superior offering has been available since long before the Drive Pak was ever created.
As you can see on the cloud9 website, the SuperIDE has tons of features and it's performance blows the doors off the DrivePack. I won't reiterate that info. Just wanted to let you know that they do exist, you will get one if you order one, and they work great. I have one myself and use it regularly. The ability to flash multiple coco roms in the different slots is super handy for some projects I work on, without that I'd have probably worn out a few eprom burners and wasted lots of time.
It sounds like a very cool device. This device and the MicroSD Pak confuse me somewhat in functionality. Most of my other similar devices (uiec, sio2sd, CF7, etc) allow me to put disk images etc on them and then boot or use them. Is that how these work? From reading the manual on the SuperIDE, I couldn't tell exactly what it did, although it did seem like it could do a lot of different things.
Yes, both the drivepak and the superide are ways to put a bunch of disk images onto (something) and then use them as if they were floppies (or hard drives, in the case of OS9).
In the case of the drivepak, the (something) is a microSD card. With the SuperIDE, (something) is either a CF card, an SD or microSD via adapter, or any IDE device.. the superide has 2 channels so you can connect both a CF/SD card and a regular IDE device at the same time as well.
The SuperIDE is a proper disk controller in the same style as the hard disk controllers that were available in the CoCo's heyday. The coco rom or os9 drivers talk directly to it as a disk device using the regular I/O area in the memory map, and any emulation of logical drives is implemented on the coco. With the DrivePak, the coco sees it as a serial port so its a little different (and a lot slower).
In the end, both will let you use modern media to store/access lots of CoCo disks. Hope that is clear