Not quite the same situation. I don't expect to have to upgrade the ipads that I bought at the same time I bought the mixer (iPad3 and original mini). It's going to become impossible to stay with MF2 in the long run since it is no longer available for any new ipad added to the system. I tried contacting Mackie about what i consider to be an unacceptable situation and got the following reply from BenO:
As you know, Master Fader v3.0 adds a ton of new UI features. This requires more CPU processing from the iPad. Unfortunately, this means that some older iPad including iPad 2, iPad 3 and iPad mini will operate slower on graphic intensive screens like mixer view, overview and the EQ. These devices are already got slower with iOS8 than with iOS7 for the same reason. For the best performance, we recommend an iPad Air or iPad mini 2 or newer.
The iPad 3 has the same CPU as the iPad 2, but because it is Retina, has 4 times as many pixels to process. So screens that require CPU intensive tasks will be slower on the iPad 3 than the older iPad 2 and iPad mini. The EQ view is the most CPU intensive screen as you make changes since the iPad needs to recalculate the EQ curve. Thus the iPad 3 EQ has the slowest response to changes.
We are looking into if there are any more performance optimizations that can be done. The EQ screen in particular is on the top of our list and is being improved for the next update.
I hope this helps.
Ben
Here's hoping!