From a VFR bimbling AV80R owner:
Is a 7'' screen so much better than a 4.2'' or a 3.8'' ?
- not too big a deal, but in general, the more the merrier.
At what size does a handheld start to become too bulky?
- anything over an AV80R/Aera/Clarity I would class as bulky, both of those fit in a pocket. The 296/496 are much bigger profile wise.
Ability to fix safely in cockpit?
- All of them do - the AV80R has a natty little sucker attachment for car/plane - depends if you want it on the yoke or not.
How important are the different screen resolutions and refresh rates?
- Depends on the CAA map/vector issue I guess. There are comments elsewhere that the Aera refresh isn't great while dragging. No problems with the AV80R - perfectly adequate resolution/refresh on that.
What do you view as crucial connections?
- USB, or non-proprietary, is important to me, as is charging off the USB connection as I always have a laptop/netbook/Vaio P with me and if I don't need to take another type of charger so much the better. I also like an SD card for storage where possible - makes copying over GPS tracks etc so much easier. The AV80R also has an e-book reader, video and audio player which works off the SD card (not in-flight though!), but what use that is I don't know (my iPhone does all that so pretty redundant feature).
What do you view as crucial battery life?
- I'm a VFR bimbler, so anything over 1.5hrs would be ok for me but depends on your missions. I have a 12v socket on the 172 and use that routinely. I also carry a few spare batteries (tiny nokia phone ones) for use in a fix.
Types of GPS receivers?
- for my application, it's not really an issue, provided they work!
If you can't connect to the internal electrics do you need supplementary batteries and what are the best sort?
- For the AV80R, it's the Nokia phone ones (Nokia BL-5C) - they give about 90mins from standard capacity, and longer life ones are available). I believe the Aera has much better battery life, but don't know about the battery pack options (or if it's even replaceable in flight).
Are all touch screens the same?
- For the purposes of these devices - pretty much. Response seems to be tied to the spec of the unit rather than the screen itself, at least from what I can tell after playing with a few of them.
Advantages / disadvantages CAA map loaded compared vector map?
- Horses for courses - I find the CAA map cluttered on such a device, and zooming can cause issues. Also, some of the info on the map is presented in a way such that you'd read it - i.e. airspace detail labels could be off the screen. I prefer the vector maps as you can zoom in/out with no loss of detail, and also declutter them - you can choose which items you have on the maps at any given zoom level so it doesn't get too crowded. For the AV80R, tapping on the airspace boundary gives you all the relevant levels etc, but I imagine it's the same on all the devices.
Updates for the vector devices are also cheaper by and large than the CAA map options, and if you fly abroad a fair bit, the CAA coverage may be moot.
Your best bet is to get to a physical shop, and play with them and see which one you like best. It's quite subjective. The Aera does look very nice however. I bought my AV80R 3 months before the Aera came out, otherwise I would have likely gone Garmin, but I have no regrets.
Hope that helps!