Like anything, it depends on the user. If you find the screen of the mini too small for your fingers, then it is too small. What other people may or may not think is largely irrelevant since we all have different finger sizes, dexterity and preferences. Go to an Apple Store or iPad dealer and spend some time with both and see what works best for you.
While I don't regularly use a DAW on my iPad (I usually use my MacBook Pro for audio recording/editing/mixing) I have played around with Auria by WaveMachine Labs on my iPad. If you are using an advanced DAW like Auria there are a lot of buttons and knobs on the screen that I think would be too small for a Mini (heck, they are small on the standard iPad). I have a Mini too, but wouldn't load a DAW on it because I think that I would constantly need to zoom in to make adjustments.
Also, if you decide on going with the Mini, go with the Retina version. The standard Mini resolution isn't very good and those small knobs and buttons will be hard to read.