AdamM No, they don't even notice, I have it on my site as a feature, but realistically no one has ever mentioned it. It's more for my exploration and fun than customer benefit, it helps with making sure no one complains about performance, but they don't go out their way to mention the higher performance.
Pursuit of performance doesn't make sense past 8-9 on the benchmark scores, past that it's just picking at straws, in K8 I can setup a WP installation that out performs my 5.2 Ghz infrastructure in everyway, but customers don't care what performance is like to a degree as long as their website "works" in the way they expect.
I have a few customers who have 5k+ products on Woo and daily visitors in the hundreds of thousands, but they just expect their site to "work" they don't care about what goes in behind the scenes. The biggest thing I have found is having a dedicated channel of communication, customers value this over any performance metric. You could have lack-lustre performance on cPanel but as long as your support is near instant, and of good quality customers don't really care.
Failure and reliability isn't a concern really as long as you have a fairly redundant backup system like Acronis etc, I always have two or three spare servers in reserve I can clone to in case of significant failure.
