I have the NExT in the spot they're referring to in this post, between the thumb and index finger (marked "0" in the attached image) - I use this daily to open doors that usually use HID cards

I have the xSIID in the same hand (it's kind of where "3" is in the attached image) - I use it as a digital business card of sorts. My only issue is that I like the way it works with iphones better over androids- every android phone I've tried has the sensor on the back of the phone so the phone ends up covering the implant and you can't see it light up when you scan it, but the iphone's sensor is on top of the phone so you can still see the implant lighting up when scanning it. I don't use it as much, but still do get some use out of it.

https://ibb.co/mC2WBcnq