Headunit with Rear seat entertainment

I have a 2012 Sequoia Platinum that comes with JBL, navigation, and rear seat entertainment that I bought early in the year. I was never really impressed with the sound quality even though I'm not an audiophile. I read that changing the headunit does wonders to the sound so now I'm looking into aftermarket units. I do use the rear seat entertainment for my kids so retaining that function is important to me. So this narrowed down my choice to
- Pioneer AVH-W4500NEX
- Alpine iLX-207

Anybody have experience with either of these units and the OEM rear seat entertainment system? Is there another unit for me to consider?

I watched a video of how to remove the headunit on the 2nd gen Tundra, I think it's the same for the Sequoia and it looks pretty easy. Is installing any of these units as easy as it looks or should I buy the unit from Bestbuy and take advantage of their free installation?

Oh another thing, there is a review on Amazon about the Pioneer 8500 and an addon to view additional car parameters and check engine lights. The review said that allowed him to view each tire's individual tire pressure. Does either of the units above or the ones you recommend have that ability as well?