Id be careful buying the idock...the ipads IOS changes far quicker than they keep up...they even stopped support on there 30pin back on IOS6...thats pretty shitty considering there were many 30pin units shipped with IOS7 and no warning from alesis.
I've always resisted APPLE and it wasn't until a few years ago that I started messing with them at all...They are generally over priced and all their proprietary bullshit bullshit..i.e 30 pin to lighning etc..bullshit money grabbing bullshit..
That all said..dammit! Their platform compensates developers better and makes it somewhat easy for developers to make and sell apps...further promoting bullshit bullshit...ugh
I was given a used duo core imac and started messing with it with Reaper and found it even though several years old to work damn well...then getting warmed up to the dark side, I bought used iPhone 3gs's for the wife and I and after we got through the itunes / icloud torture they worked damn nice.. just upgraded a few weeks back, bought two 32 gb iPhone 5's for $550 used and after going through the itunes / icloud torture of getting our contacts and such switched over they work way awesome..
Picked up a iPad 2 for the wife / granddaughter @ 6 months ago, then one for me to play with a month ago ..Have about $500 invested in both with cases ...at that price it is acceptable at the new prices ...fahgetaboutit.
In regards to interface for the iPad
After fighting through the Behringer is202 bs I opted for the iConnectivty midi2+ I do like this company as they are pretty clever ...that little $89 interface ( sans the damn 6 volt dc adapter ) is pretty slick and the software to route and work with so far is damn deep and cool. using the ipad as a sound module the midi2+ routes the audio back to my computer magically via midi..wtf!
I used it last night for practice with the band ( just using the iPad audio out to my amp) and it worked flawlessly ..well sort of...my Hammond app Galileo hung on a note in one song.. BTW the midi2+ charges the ipad as it is interfacing with the midi keyboard with the optional wall wart that I already had in my arsenal of 50+ extra wall warts
As a keyboardist having played with a lot of synths and keyboard toys over the years these apps for $10 to $50 are flipping bad ass...having fun but there are definitely limitations due to the apple way of doing things their money making way...