I have an AppRadio 2 and in iPhone 6 on iOS 8.0.2. AppRadio mode works OK with some glitches, so I'm exploring  my next head unit. 

Sorry, I know this information might be buried on one of the other threads. But just this once I have to be *that guy* who asks a question that's already been answered. I read in the article linked below that "Pioneer added CarPlay to heads already equipped with AppRadio Mode, Cardenas said, because “there are distinct differences between AppRadio Mode and CarPlay.†Depending on how they connect their Apple 5, 5c or 5s iPhone to the head units, consumers will be able to choose one feature set or the other, he said."

http://www.twice.com/news/audiovideo/pioneer-carplay-appradio-perfect-together/2532

I think I like the AppRadio 4 for my needs, but based on this chart and the article above, it seems like I'd have to choose either Appradio or CarPlay. It doesn't look like I'd be able to use both without changing the cables around, which is severely impractical. 

Is that what you guys are experiencing with the NEX units? Can you have access to both AppRadio and CarPlay or do you have to choose one or the other? Thanks!

You have to choose. CarPlay uses lightning cable directly to usb1, and smartphone cannection set to usb and CarPlay enabled. AppRadio uses apple a/v adapter which hooks up to hdmi. AppRadio connects to iphone via BT, and audio and video is sent via hdmi. When hooked up for AppRadio, lightning cable from apple a/v adapter only charges phone, so it can be hooked up to either usb ports or to a car charger. If it us hooked up to usb on pioneer and you choise usb as input, it will give errror code "no compatible device".

Thank you for the clarification. 

Do you know if video podcasts come through via CarPlay or any video for that matter, as long as the car is parked, of course?

Not sure, but i dont think so. My messages did not show on screen, they were read to me. I do not use CarPlay, it offers me no advantage over appradio or just BT and usb1 connection via lightning cable. 1 thing i do is hook up hdmi via apple a/v adapter and mirror my phone if i want to play hbogo or maxgo, etc. you do this by choosing hdmi as input and keeping smartphone set to usb.

Is there any reason to apply the update if you not using an iphone? but use an iTouch.