These have been durable and worked spot on once i sorted out the Bluetooth issues. WindowsMR does not like certain onboard motherboard Bluetooth adapters - it will work, but drop out here and there giving the illusion that the controllers are problematic. This couldn't be further from the truth once you fix the issues. Once i installed a USB Bluetooth dongle, they are 100% accurate. Every movement and button press registers. As for losing tracking behind the back, it simply has not been an issue for me - perhaps i'm playing the wrong games but it's never been a problem.
It helps that they seem to be designed to take beating. If you have walls or hardware too close to you play area, they will. Mine are still working fine despite both me and my 5 year old finding our "boundaries" the old fashion way.