Just wanted to pass a little bit of information along to anyone considering going the Garmin route.  I recently added the new 741 chartplotter, with the 18HD radar, nmea 2000 net, wireless wind vane, and depth/speed/temp transducer.  The reason I went with garmin was because from all their literature it seemed like it was well integrated with Apple i-devices.   The plotter itself works well with other garmin components, but I have yet to get it to do anything with my ipad/iphone other than skip to the next music track and adjust volume.  So, I have update the software on it, because it doesn't work at all with the iphone garmin helm app.   
The largest problem I have is, Garmin doesn't provide any way to download software updates for the stuff on a Mac.  You have to have a Windows machine with an sd card slot to be able to update the equipment.   I have like 15 Macs and ditched windows around 2002 because it's basically useless (in my opinion...) Last weekend, I gave up trying to get virtualbox with windows on my mac to work with the SD card, and bought a cheap windows laptop so I could upgrade my garmin gear whenever I want to.  So... If you're not a Windows person, then you have been warned.  You will need a windows box if you don't have one, so if you're going the garmin route, add that to your pricing.   Garmin will sell you an SD card for $30, but who wants to pay for something that's free to download to fix bugs in THEIR software?  It doesn't add anything new as far as i know, it just makes it work... I already paid for something that's supposed to work, so basically, that's just bad customer service.  IMHO they should mail them to me for free upon request given the amount of money I've spent on their gear.  I'm pretty disappointed by this, since updating should be much simpler given that the chartplotter has wifi, bluetooth, usb and nmea2000.  Kind of a brain-dead hurried design imho...  So... if i could do it again - I'd probably look more closely at their competition.