I’ve used phones, Zumo XT2 (still have one on my 701), but I’ve been using the DMD T865X since late March on my 501, and I’m all in. I’ll convert the nav bar on my 701 to use it as well this winter. DMD also make a smaller screen device, but it lacks a few key features that the big one has.
On youtube, look up Robert Baldinger’s DMD videos; he a Swedish dude that does a great job explaining the device and software detail. For me, here are the key factors that make it so good:
• same screen brightness as a Garmin
• the GPS chip refresh rate is 10x (yes, ten times) faster than an iPhone or Android phone, so there’s no lag, and you’ll never miss that turn.
• the default DMD nav software is really well done.
• it’s an Android device, so it’s seamlessly integrated with Google Drive, Dropbox, etc. Adding a track is as simple as opening Google Drive and selecting the .gpx file. It automatically shows up.
• it’s an Android device so you can bring Netflix or whatever apps you normally use with you on tours. And it runs Google Maps, Gaia, OnX, and anything else.
• it has two SIM slots so it can have its own cellular service/phone number. Or, you can have it piggyback off your phone when you need service. I do the latter.
• it’s waterproof, as is the powered cradle that holds it
• if you have a modern bike, you can make it talk to your bike and get all sorts of information on screen from your ECU.
• there’s a hardware button that turns off screen input when it’s raining, so no phone shenanigans.
• the larger screen is nice for geezer eyes.
• There’s a super active Facebook (ugh) user group, and the lead Software Developer is always in there as well. So when you have questions, that hive mind is top notch, and you often hear from the guy who can fix any bugs you find.
You can also run DMD software on other Android devices of your choosing, but they won’t have the level of integration that DMD’s own device does.
Oh, and in the States, ADV-TIM is the distributor. https://adv-tim.com
Lastly, have a Zumo XT2 for sale if you want to go that route.