Not to budge in on a conversation, but I would give a few words of advice since I use mine in my duck boat for small lakes and also for ice.
1) Unfortunately you only get 20 and 60 degree with the helix unit, even with the ice ducer.
2) you can toggle both frequencies just fine and also show both on a split screen.
3) the DI ducer is a PITA once the ice thickens, like fishwater says.
4) yes, the ice ducer has a temp reader in it.
5) as far as I know, you cannot easily switch between both custom modes. You can easily switch between their “ice” mode and “open water” mode, however. But I have found that just switching it to Ice isn’t what I like. I end up spending 20 minutes or so switching back ALL my settings each time. If someone knows more than me, please chime in.
6) I unplug mine and switch batteries all the time, it saves settings.