Short answer: Yes, absolutely.
Because the iPad 2 is the last iPad with a non-Retina display, MIDI Designer Pro 2 is actually quite snappy even with a huge layout (like this one), and it works quite well.
On the other hand: the iPad 2 is quite slow with iOS 9.3.5, and MDP2 doesn't look beautiful and wonderful and non-Retina resolution. But it works and it's actually nice and fast.
So: will it work? Yes, absolutely, and you'll be able to design your layouts and control your gear quite well. Would I recommend it? Well, if you can get an iPad Air or an iPad Air 2, do that! Check out the refurb deals from Apple.