945 LTE Assistance Plus

The watch has a much smaller battery, transmitter and antenna so a phone will have the advantage in a weak signal environment. A phone can also operate on more bands and can roam to other carriers towers to make a 911 call.

The benefit of the LTE watch is just that it can call for help without having to carry a phone, but it isn't going to work miracles out in the backcountry with no signal. You'd need inreach for that.

Good comments and thoughts.

The OP also wondered specifically about comparing the Apple Watch LTE vs 945 LTE.  I would (probably incorrectly) assume the differences may be generally small and very case-by-case - i.e. the radio and antenna design in each may specifically make one better/worse in a given environment (i.e. specific carrier towers and bands used in the region)?

Of course even a small difference may seem significant if you need it and one of the devices would marginally connect while t he other not.

My question centers more on the reasons Garmin opted for LTE-M which is a low power, narrow-bandwidth network technology that also has significant benefits such as deeper signal penetration through buildings and underground. I sense Garmin’s engineers were thoughtful in their decision to adopt the LTE-M network standard but the advantages were not well explained in the marketing of the device. Combined with the IERCC, the 945 LTE may have a real advantage over the Apple Watch GPS+Cellular in emergency situations. I’d love to see a Garmin engineer shed light on this topic because it seems like the 945 LTE is under-appreciated. 

I think it's pretty clear they chose LTE-M for the battery life. I personally don't think LTE-M has any signal or propagation benefits over a full LTE modem as in the Apple watch. Even if it does, it's limited to a single band on the at&t network. An apple LTE watch calling 911 is able to use virtually any tower in the country.

I don't mean to say the Garmin isn't a good product, It's great to have that peace of mind that assistance plus is there and the watch still has excellent battery life.

In the FCC filings for the watch it uses At&t's bands (2,4,17). Also the coverage map on Garmin's website is AT&T's. This is for for US version, of course.