Sorry so long winded:
First I wouldn’t rely on an HT even if attached to a mag mount. Yes, it may be heard, but a lot of the time it is broken. For general use this may or may not be OK but when working a public service event, the last thing net control needs is to have is to try and pick out what someone is trying to say. If CARA uses their portable repeater, this will make an HT useful as was the case with the Cochrane Winter Rally. However, for most on the Kananaskis Rally, the HT would have been useful only for cross band repeat. And I did use an HT for both these functions but used for cross band at the Kananaskis rally. For the MS Bike Tour, I only use HT for cross band.
I know a lot of people are promoting D-Star and Fusion for emergency use. But when the internet goes down, I doubt if these digital modes will be that useful as they both rely on the internet. A possible more useful digital mode would be the HF digital modes that don’t rely on internet. Or some digital modes like Fidigi on 2 meters.
D-Star to me is a little complicated to set up but once set up is OK. I find the quality a little bit less than desired but useable. And there are a few repeaters in Calgary, Airdrie and SW of Calgary. Fusion, I believe only has 1 repeater in Calgary and a couple of simplex frequencies, 1 on 2 m and 1 on the 220 band. Much simpler to use. I can’t really comment on DPRS except it will not beacon with the Kenwood or Yaesu APRS directly.
As to radios, you have had a couple of responses on RadioReference. Personally, I find the Yaesu FTM-400 much easier to program and use than the Kenwood 710. I like the Yaesu as most of the functions including scan start and stop, can be done on the microphone [Kenwood has programable on mic as well but no scan]. And with distracted driving I can use the mic easier to do what I need the radio to do without having to view the display or even look at the mic. [I won’t get into distracted driving with more than the PTT on the mic]. The Yaesu mic has 8 programable buttons while the Kenwood has 4. While the 710 has a decent display, the display on the FTM-400 is great.
The APRS function on the Kenwood is far more complicated but one can do far more with it. For my need, all I require is for it to beacon my position and to receive others. I do not use it for messaging although both can do this.
The Kenwood has more functions on how cross band repeat can be set up. It allows some functions that are not necessary in Canada such as being able to automatically identify. But I find the 400 very easy to set up and has served my need well in all the functions I have used it.
Comparing receive on both, I seem to get more QRM on the Kenwood. In fact, it will have interference when the 400 doesn’t. The 400 will display the volume on the display whereas the 710 doesn’t however, the squelch setting on the 710 is displayed and the controls are on the buttons on the display head whereas the squelch on the 400 has to be changed by going into a menu. But I find I am always changing the squelch on the 710 but only need to change it on the 400 when I need to turn it down.
I have had good luck with all the Yaesu radios I have used with little if any problems. I haven’t used Kenwood radios long enough to give my opinion. And I really like the idea of programming the 400 with a SD card vs having to take a computer and cable out to the vehicle to program the 710.
The 400, if using an external speaker, requires a special connector that is included with the radio, or having to use Yaesu external speaker. I find overall, the volume output on the 400 louder than the 710 through the external speaker. I haven’t compared them using just the speaker in the radios. The microphone does not come with an extension for the 400 but it is easy to make. All other extension wires are included with the 400 but may need to buy a kit for the Kenwood. One deal breaker for me [but may not for others] the 400 can listen to the AM Air Band 118-136 on both bands whereas the 710 the AM air band is only on the A side.
As others have said, use a very good antenna.