Best inReach unit for ultramarathon tracking

The original Mini had a problem with slow acquisition. Anecdotally, the M2 appears to be somewhat better than the original Mini. Personally, have never had a problem with acquisition on any iR device except the M1 and M2.

I was unable to find specs for transmit power on any inReach device. If you really want to know. you'd have to open a support ticket.

Garmin doesn't mention heavy canopy in their guide.  They refer to "moderate tree cover" for the Mini2 battery guide.  They are definitely letting people know that there is a significant difference in battery life depending on the view of the sky for the Mini2.  I assume that applies to all inReach models but not sure.

support.garmin.com/.../

I bought a 66i for hiking/camping, but for running, I would definitely go with Mini2. Garmin released the Mini2 in winter so it hasn't seen a ton of real world testing by users hiking in eastern half of USA, for example, in dense oak/hickory canopy...so not a lot of reports.

I bought my 66i in winter and haven't tested it in dense oak/hickory canopy yet (no leaves on trees yet).

The 700 series is too big to take running (imo).

https://support.garmin.com/en-US/?faq=FrvUD8cBa53K4MRV1f75g5

www8.garmin.com/.../GUID-D9DEA9AC-8107-4A2F-9A4E-E5A0B4A7EC3C.html

Any issues with canopy apply to all iR devices. The mention in conjunction with battery life has to do with the way the iR devices handle retry. Whenever you send a message or request an active message check, the device (re)tries really, really hard to complete the operation. In poor conditions, such as under heavy canopy, it may take a lot of retries. This is a real battery suck. The iR modem draws a lot of power during transmit.

Note that wet canopy is much worse that dry canopy. 

Given that the iR frequencies are close to GPS frequencies, I would expect there to be issues with some (long) needle canopies as well.

The specs (according to the manual) for the Mini 2 state that on the 1.6 GHz Iridium band the transmit power is 31.8 dBm.  That is equivalent to slightly over 1.5 watts.