In Dash or Ram Mount?

[Eesctom]

I'm still deciding on a gps/fishfinder and was wondering if anyone had any opinions on mounting. I have an X-96 in the dash but was considering a HB 798 HD Si or 898 si unit. I was planning on mounting the unit in the dash but it occured to me that if I do a RAM mount that I could have my boat rigged for trolling motor and transom mount and just move the unit around so I have the ability to use it in both places. Does this make any sense or am I missing something? The one downside is I could see myself dropping the unit overboard while switching it around.

Also what would I do with the in dash unit that there? Just leave it?