I'll just chime in since I own a PCR-300 (just bragging, not complaining)...
Anyhow, I understand your desire for an easy to use interface. After getting acquainted with the PCR, after reading and posting here and watching just a couple of YouTube videos (yes, there is a guy out there showing some nifty short cuts in programming) that really helped me. Now I am very comfortable using it. It isn't that complicated as it seems (like most things, I guess).
So now consider if you like the layout. For instance, I prefer the transport buttons on the left side like the PCR instead of the top just above the keys on the A-PRO. The more appealing feature the PCR has over the A-Pro is that is has 18 pads (yes, I said EIGHTEEN) for drums, samples and/or triggers (for sample or loops) or whatever you want them to do. So more buttons on the PCR, not the A-Pro, it has only EIGHT! Both have nine encoders (or nobs) and nine faders (of slide controls) They both seem to share the programming controls, the same combo modulation/pitch bend stick (a Roland trademark) and both have inputs/outputs/plugs on the left side (very convenient. The only other distinctive differences between the two may be the display which is no concern for me; the PCR has a metal like plate around the knobs, pads and sliders AND the PCR has what my be completely useless or a convenient pan control or DJ style crossfader. And if you are a control freak like the most of us, you will note that the PCR has a total 50 fully assignable controls whereas the A-Pro falls short of that by 5 less. The bundle software is different, but if you are already using SONAR, who cares? This could be a lot to consider. But then....
Now ACT is ACT and it may not make a difference which SONAR friendly controller you chose. At least that is what I am going with. The PCR is easy, very easy to program. In fact, you can always save as many assignment configuration files you want on your PC and transfer them to the PCR with out a hitch (just hit the right button is the correct sequence, but it is really simple, trust the Rocker!). But I suppose the A-Pro will have the exact same functionality.
So, to sum it up... The PCR is actually very easy to program and use as an interface for SONAR. It's little brother, the A-Pro, is just as easy I'm sure. It may be a simple matter of more controls or appealing layout. Either one won't do you wrong, but I'm sold on the PCR.
Kind regards,
Living Room (The) Rocker