I had the 441s and I liked it, but the screen was too small and it was SLOW to work with. I got it off this site used for a good deal so I couldn't complain.
Go with at least a 7in display. I use my Note 2 with Navionics and it shows speed in GPS. I use my depth sounder for real time depth of course. It has a 5.5 in screen and I use a windshield mount. couldn't be happier.
In all honesty if you have a depth sounder (you should) I'd purchase a Nexus 10 google tablet for $400 and get the $35 Navionics HD app. The maps are downloaded, no internet/wifi needed. If you don't have a sounder (weird) just installa Faria one with depth and water temp, they're cheap.
http://www.overtons.com/modperl/product ... gi?i=74431