Ok! Thanks for your info!
By what you describe, for sure you have no problems using voice control over Bluetooth because you are using Siri and not the Voice Control native feature from iPhones since the first one I believe.
In this thread many people says that are not having Bluetooth problems with Siri, but with Voice Control.
To activate Voice Control instead of Siri, go to Settings > General > Accessibility > Home Button and Choose Voice Control by checking that option under the “PRESS AND HOLD TO SPEAK”.
Then your iPhone uses the Voice Control feature with voice commands and not Siri.
About your answer “Are there any disadvantages to using Siri where someone would be using Voice Control instead”. Yes!!
Please read this discussion, at the third or fourth post I talk about it and hopefully you will understand why.
Going back, about the firmware updates of Bluetooth devices, what I believe is that you are partially right on what you say about it, but only when the Bluetooth device, just stops working at all with another updated device. Meanwhile, a good engineer that develops a new OS, must be competent to not develop a new OS that just make your phone incompatible with the major Bluetooth devices, inclusively their own make devices as the Apple’s Bluetooth Earpods that it seems that even with them you have the same problem.
So, the problem is not really the firmware of your Bluetooth device, but the mess that Apple´s engineers have made with this iOS 11. Not just Voice Control is broken but numerous bugs are discussed here and out there after iOS 11 update.
By the way!
I’ve also updated today to iOS 11.1, and… , bad news!! The voice Control feature remains with same problems, over or not on Bluetooth.
Shame on You Apple!! How can your engineers be so incompetents?!
If not the so many unsatisfied users about this bug to be considered as an important issue to care about, Even your Bluetooth Earpods are expensive enough to let it be a peace of trash as a non-useful hands-free earphones.