I'm toying with the idea of upgrading to a 750 (I'm blaming it on something in the water impairing good financial judgement).
That big screen is very enticing... And it was a lot of money, but I don't regret it at all.
Is the 350c audio panel a separate box in the stack, or a remote box operated through the 750's touchscreen display?
Either! There's both a panel mount version as well as a remote version that can be controlled by the GTN 750. We chose the panel mount version, but mainly because we had lots of room, and chicks dig panels with lots of buttons.
Also, if you have the remote version, part of the area at the top of the GTN screen is used up by the audio panel controls, while if you have the panel mount version you can have four extra data fields at the top of the screen. I really like having those extra fields.
How does the 350c voice recognition work? Is there a separate "PTT" so it knows you are talking to "it", instead of passengers or ATC?
Yes - It's "PTC". Push to Command.
Can you ask it to switch functions and will that then cause the GTN to change page display?
Yes. Every page in the entire GTN interface has a voice command. So, you can hit the PTC and say "Show destination airport runways" for example.
Any other insights, pros, cons, what you like best, hate most, about that combo appreciated
The worst part is what one other poster talked about where some functions of the audio panel kinda end up requiring the manual because (1) they're rarely used and (2) they require a combination of buttons. But because they're rarely used, it's not really a big deal.
It's really nice to be able to do the voice control, though. Commands are in several groups:
1) Audio panel commands. You can say things like "Toggle COM2" to turn monitoring of COM2 on/off, and "Select Mic1" for example. I pretty much don't use these though, because we do have the panel mount version of the 350c so there's a button right there.
2) "Show" commands. Like I said, any page in the GTN interface. I use this a LOT, often to quickly switch to the Traffic page for example. There are also some things that you can get to display on screen briefly like "Show desired track" but I rarely use those because I prefer to have data fields on the screen already for the ones I use the most.
3) "Tune" commands. Say you want to pick up flight following, you can say "Tune nearest approach". If you're getting set up for an instrument approach, you can say "Tune destination tower."
4) "Say" commands. Don't have time to look at the screen right now? "Say ground speed" and Betty will tell you how fast you're going in your headset. If you have any sort of air data computer hooked up to it, you can even "Say winds".
It's pretty dang cool. Avionics shop owner tried to talk us out of it originally, but once he saw it in operation he said he was going to have to put one in his plane.