As Talbot mentions, Simrad AP's have a reputation for reliability and robustness. I am going N2K for the boat, hence my preference for the RF25.
The Maretron GPS is 5Hz and is updated for the latest magnetic variation per the Panbo entry here
Also some good dialogue on H2183 by Dan Corcoran on Panbo here.
I don't anticipate problems interfacing with my Furuno NN3D MFD8, but as they say "in theory". We are currently on Lake Michigan but have not decided where to commission our V42.