In my case the whole interest with braces / retainers was the having the plastic there and talking and eating with it all the time, no option.
Not much different to denture wearing I suppose.
I really don't know how many others feel the same.
When I first got a retainer it was very strange to have it in for eating ( and speaking, of course) but after a few weeks it was really strange the first time i finished a meal and suddenly realised that I had forgotten the plastic plate was there.
Now I find it quite difficult if I take it out to eat because the roof of my mouth is super sensitive and gets sore with any hard food, and I have to concentrate to talk clearly without it.