I’ve got an Alesis I/O dock. I like it for the sturdiness of connector; since it’s in a “dock” I don’t have to worry about a dongle disconnecting with movement. Also holds the ipad at a nice angle.
Doing this right now, actually got a really cheap usb to midi cable off amazon just so I could use some midi gear into my desktop at the studio (have an apogee duet…no midi) and it works great plugging it directly into ipad via the camera connection kit. No external power source or hub required, sequencing Waldorf Nave and resampling it into OT, sounds awesome. YMMV with the cheap usb to midi cables though, mine is just some no-name brand. I also have the griffin studio dock which is great for sampling the OT back into the iPad.
I use a powered USB mixer, powered hub, a USB/midi cable, and a couple USB controllers via the CCK. Works flawlessly, MidiBridge sorts out the routing. I’m doing this with the Monomachine, but that shouldn’t matter. MNM set to autochannel, so I can sequence (or play via the keyboard) internal and external synths simply by selecting the track.
I’ve got a Novation X-Station on the way, which should simplify this setup, but the main things to look for are class compliant devices, powered whenever possible.
The biggest issue is that I can’t power the iPad while using it, which limits how long I can really use it as a production tool (and is also another reason I’m buying the OT in a week or so, so I can sample from my apps). If you’re using a Lightning enabled iOS device, options are pretty limited right now, so you may just want to hold out until NAMM to see what comes out.
Tried but hated the weedy loose feeling of low confidence when using midi/audio interfaces connected via the camera connection kit, especially on ipads 1-3. Worked but cables just kept on popping out.
Bought a behringer IS202 about a year ago and its been flawless. Sequencing via Monomachine works fine, charges while using, comparitively sturdy, midi + audio + battery powered + more. Sounds pretty decent, though I am sure the RME beats it, but for $180au its better than I expected.
I planned to grab the alesis dock but side by side the behringer had more, felt a little sturdier & also allowed sysex midi in/out(great for lemur, app editors etc).
I would love to see one built specifically for the ipad mini, maybe in time.