I do this cool thing where I go to my store. And I ask to try the headset I'm interested in. I get personal hands on experience. I connect it to my phone, and to my watch. And I see how it handles two connections at the same time. It's not rocket science.
Yeah, that's not really an option where I live (New Zealand). We have very limited choices of both physical stores, as well as models available. In my case, the WH-1000XM5 wasn't available in any physical stores when I bought it, also, I ordered it online directly from Sony (another reason for ordering direct from Sony is I get a discount thru my company).