Around 3y of flying with single GDU 460 and a 305 here.
In my experience, IFR- particularly the approach phase, using the screen is pretty much a no go if you only have one GDU.
Also the added redundancy of having an autopilot if the GDU goes dark is important.
I?ve had mine go dark once, thankfully VMC.
All depends on your mission. VFR can live without. IFR I wouldn?t.

Richard are you using the display full screen or split? I always fly split screen with the ElFIS on the left and map or approach plate on the right. I do not have the 305 so I have to tap the AP control on the top of the EFIS to bring up the autopilot window on the right side. I fly IFR with this configuration and I don't find myself wishing for more. The EFIS is always up on the left half and the plate or map is only covered up with the AP control screen for a moment, then put away.

I thought I was going to want the AP control head but the only thing I wish I could do is install a discrete button to activate the right side control screen and then put it away again with the same button.

I think if I had gotten used to the control head I probably would think I couldn't live without it.

Jim

Hi Jim.
Yes this is pretty much how I am set up as well.
For me the issue is more one of unwanted PFD changes in the approach phase.

In my view having any PDF configuration changes while flying an approach in IMC is not risk free.
My approach checklist bans all touching of the screen past the IAF.

Also, It?s pretty easy to have more than one go at something on the touch screen if it?s bumpy. The touch screen requires 3 discrete touches to achieve the same as one touch on the GMC.

I agree you?d be pleasantly surprised at how easy a GMC would make your life :-)

I just upgraded from non touch dual screen to single touch large screen. No GMC room on my panel so I go without. I've been playing with it IFR, coupled and have no complaints. It can't definitely be left out and considering how huge the GMC is (really Garmin?) I suspect some will leave it out. I am content without it.