I currently work for Best Buy as a Geek Squad Delivery Agent. I have installed several Vizio TVs this year (both M and P series) and I have an E series mounted in my living room. I have experienced some things with these TVs that may be helpful to you.
Vizios have a very good picture. You would need to get a very high end Samsung or LG OLED to get better picture quality. Vizios tend to need a little more tweeking as far as color temperature and audio sync out of the box, where Samsung and LG TVs (especially Samsung) are pretty much at best picture quality out of the box.
Where current Vizios suffer is in their smart apps interface. The UI is slow, and the apps can be buggy. Even on P series TVs. I believe Samsung and Roku have the best TV UIs available right now. But having Chromecast built is is very nice. I was very happy to see that with Vizios 2020 TVs, they are targeting UI performance with Smartcast 4.0 and upgraded internals.
On reliability, our TV repair techs tell me they tend to replace back light driver boards more often on Vizio TVs than on other brands. But their reliability is on par with other brands.
And you are correct, Best Buy employees are not paid on commission. The in-store associates do not have as much experience with actual set-up as the Geek Squad home theater agents.
I hope this helps. Let me know if you have any questions.