I might not be the best guy to answer this but I have been trying to stay up to date on the capabilities of each model. I own the older HDS gen 2 units.
Here is what I’ve heard.
HDS Gen 2: Not compatible with viewing created maps.
HDS Gen 2 Touch: Not compatible with viewing created maps. Not as user friendly due to lack of any buttons.
HDS Gen 3: Fully compatible. Slower processor than the Carbon.
I may be wrong on the Gen 2 Touch compatibility though.
I will respond to this to add clarification:
HDS Gen 2: Not compatible with viewing LIVE created maps like the new functionality added by Navionics this year. You can record your own sonar data, upload to the cloud community, the file gets transformed and then you can download to a blank SD card and use in your unit. Lots of steps, doesn’t work that well, but I have done it and it does work.
HDS Gen 2 Touch: Not compatible with viewing LIVE created maps like the new functionality added by Navionics this year. You can record your own sonar data, upload to the cloud community, the file gets transformed and then you can download to a blank SD card and use in your unit. Lots of steps, doesn’t work that well, but I have done it and it does work.. Not as user friendly due to lack of any buttons. Agreed. Also, you would have issues if you wanted to use it icefishing or on an ATV or something because of the touch screen grounding issue, but some have gotten around that.