On my GB 32 I have used Navionics+ on my iPad for a couple of years now and really llike it. It's backup to the Raymarine Axiom 12" MFD with Navionics, but the iPad version of Navionics is actually easier to use than the Raymarine version. And chart updates are easy-peasy. I also added a Vexlar bluetooth depth finder which shows up on the iPad Navionics screen. Transducer is mounted inside and shoots thru hull, so installation was easy. At about $150 for the whole thing made it a no-brainer and now the iPad has everything he Raymarine unit has except integrated radar. Also, since I only have Raymarine at the lower helm I can take the Ipad "upstairs" and use it with the Navionics app or mirror the Raymarine display, including touch screen control. So the Ipad saved me the whole cost of a second Raymarine display unit on the flybridge.
Smooth seas and fair winds,