I had a similar experience, at least in perception. My battery life won't last throughout the day anymore, but I do not think the 80% setting is the cause just yet.

I used the 80% limit for awhile, some time later I started turning my phone off at night with my phone on the charger. With the phone 'off', it would charge to 100%.

Now it feels like it doesn't hold a charge as well, but no actual tests were performed.