compositionally, you can take koala a long way towards what you can do with an SP404MK2 ... but it's a significantly different experience. You might prefer one over the other, or what the SP404MK2 affords you in terms of tactile experience might not be worth the expense.For those of you using SP404MK2 and Koala Sampler, can u compare these two?
A SP404MK2 + iPad is a really great pairing though. the SP404MK2 works as midi input/controller + audio interface for your iPad music production rig, as well as being an SP404. So as a long term goal, even if you're getting by just fine with Koala, there's probably some legit gains to be had by adding a SP404MK2 if you can afford one. Also, Roland have been really showing the world how it's done in terms of long term support.