Yes, I've read it. Most people on the reprap forum (not the one on this forum, the one from the reprap website) advise against them whenever they are brought up. Feel free to ask there if you don't want to take my word for it.
The reasoning behind it is that people usually went to avoid elasticity from things like belt stretch, so adding a literal spring (something designed to stretch) is detrimental to that goal. If you tension the belt properly, there shouldn't be any slack for the spring to take up, seeing as you won't take my word for it go ask the manufacturer.

I doubt you'll actually read these since you didn't look at the wikipedia link I sent on bang-bang control, but since you asked for them I'll oblige:
https://reprap.org/forum/read.php?1,799484,800159
https://reprap.org/forum/read.php?1,802522,803027
https://www.reddit.com/r/Reprap/comm...elt_tensioner/
https://www.reddit.com/r/3Dprinting/...ng_tensioners/
https://www.reddit.com/r/3Dprinting/...ually_helpful/
https://www.reddit.com/r/3Dprinting/...lt_tensioners/
https://reprap.org/forum/read.php?14,836414