Ooooo, I always love a chance to spend other people's money on avionics.
It sounds like you're in the experimental world, so it won't be nearly as expensive, either...
I would go with the single 10". That gives you some flexibility: You can switch it between full-screen PFD and combination PFD/MFD. I'm expecting that when I get the G3X, for example, I'll probably switch it to full-screen PFD when I'm on an instrument approach.
Given how cheap it is to do this in the experimental world, I'd say it's a no-brainer. The Garmin autopilot is fantastic. I fly a GFC700 in a TBM at work, and the GFC500 is every bit as advanced and then some - The 700 doesn't have the envelope protection, LVL button, etc. I've flown behind a friend's GFC500 and was really impressed.
If the 930 does what you want it to, I would keep it... With one possible exception. Do you like to, or expect to, analyze the logged data (I do)? If so, I would integrate it. That way, you can put the data logs on a laptop, and if you find some sort of an anomaly like a high CHT, you can also look at what the OAT and airspeed were at the same time and see if it's really something that needs to be looked into further, or if other conditions were affecting it. This has saved me money on maintenance and improved my training in the past, so I'm a big believer in it.
However, if you're not going to look at those data logs, I don't think there's a compelling reason to ditch a perfectly good 930 to have it built into the G3X.
And both devices will still log data, it just will be necessary to ensure that either the times are the same on the devices, or join it together in some other manner (more work).
Now, as to the question you forgot to ask:
4) Should I switch out the D10A for a Garmin G5 (or add a G5)?
Personally, I would. Not that there's anything wrong with the D10A, but there's some things that you get from the G3X + G5 combo that I think are very compelling.
First of all, you get miscompare monitoring. If you have some sort of AHRS problem with one of them, they'll both squawk at you. It might still be worth keeping the D10A so that you have a tiebreaker I suppose.
However, one of the other nice things with the G3X + G5 combo is that they'll communicate with each other over the CANbus so that you only have to set the altimeter setting and the altitude/airspeed bugs in one place, and the autopilot mode will be communicated over as well. So, let's say you put the autopilot in FLC mode at 100 knots, preselect an altitude of 5500 feet, and set the altimeter to 30.14 or something on the G3X, both the G3X and the G5 will have bugs at 100 knots, 5500 feet, an altimeter of 30.14, and FLC ALTS GPS as the autopilot modes, for example.
Finally, both the G3X and the G5 have the capability of being the brains of the autopilot. Let's say you're flying along, about to intercept a final approach course in IMC. You're all set and ready - Autopilot is on a heading to intercept, approach mode is armed, and altitude hold is on - When bam, the magic smoke escapes from the G3X and it goes dark. Not only does the G5 already have all the numbers and modes, it will take over as the brains of the autopilot and guide you onto the final approach course and down the glidepath! There really isn't anything else like this in GA, and it could really save your bacon in an emergency.
Thanks for the ping!
