I've had similar experiences to OPs with older Bluetooth mice and keyboards, so I was reluctant to try the Logitech MX Master. The only reason I did was because it offered the optional Unifying receiver. Well, I haven't used that receiver yet, because the Bluetooth was very easy to pair, and I haven't had a single connection issue (delay or otherwise) yet. This thing has restored my faith in Bluetooth devices, when done right.

Good to see not just Apple users and with that may be as many chipsets out there that some work better with others as is the case of any communications device and that said. Like to like chipsets would generaly be betetr, which is what you would expect from Apple, though again they diversify on chips so again moots that you have verbatim chipsets in part.

Me I've been lucky, though not a heavy BT user, so that may be the crux. This and then you have other things like wifi and interference from many things that could curtail signal

But for a keyboard right next to a device I would expect that to be less of an issue.

So with drivers and chipset variations, and quick google shows, can be some fun and games. But true of any digital communication device, will always be not perfect.

But in general I wonder if those who have had issues, have seen them get worse over time with BT or better? I know people who have had issues and a later driver fixes that issue, even instability ones outlined.

I have similar experiences. Bluetooth headphones on the phone have never been an issue, but the same devices become unreliable when paired with a PC.

Funny enough, my Bluetooth headphones (LG Tone something or other) has been rock solid, the only Bluetooth device I can reliably trust. My mouse, my keyboard, my Pebble, my literally everything else Bluetooth, all have failed me. My Bluetooth headset is the only thing I've never had a problem with on mobile or desktop.

My bluetooth mouse, my android wear watch, and my wireless headphones all work fine with my computer, and phone. So I share the same thing as you were I see no issues with bluetooth. Even my car does bluetooth without any problems. It sounds like OP is experiencing driver issues rather than specific device issues.