Just got one in today. I won't be using the steering wheel controls, don't have. I'll post when I finally get it done. It is being used by Explorer van on their conversions. I saw one with a Pioneer unit installed. I ordered it through them.
Did preliminary install. It all works first go! Kenwood 694S Nav head unit with Sirus. Just plug and play with the RP4.2-MB11. Some slight static/interference with factory reverse camera but have same thing with my other Kenwood 594 install. It took 3 different cameras before it was clear on that one!
I don't have steering wheel controls so I can't verify that aspect but I sure would give it a go.
On to the next part of the install. Honestly, if I had tried it before buying all the other things I may have been satisfied with just the Kenwood deck. The higher power and adjustability made a huge improvement by itself. Next speakers and amp.
PS, got better price than $229 and don't remove the knobs on the AC switches!