Hey MWH,
The problem with devices that store the EDID is that they never work or the HDCP never passes.

What you want is the KeyDigital KD-Pro4x1
It’s a 4K 4 in 1 out switch with audio out (digital coax and 3.5mm analog).
The special part is the EDID switch, let’s you select a fixed output and leave it there.
I have installed hundreds of these, it’s a solid purchase.
Does 4K 4:4:4 up to 60Hz.
It’s IR, RS-233, and IP
Works with Savant, Crestron, Control4, RTI and just about everyone else.

http://www.keydigital.com...Pro4x1&Company=KEY

That KeyDigital KD-Pro4x1 looks to have the exact same feature set as the Extron 4K Plus, so I'm a bit skeptical that it would offer a different experience.
 
The problems we're having with Extron's switcher are two-fold: when switching inputs, both connected computers' displays blink out and then the come back on with the desktop moved to the projector for the PC that is connected to the selected input. The other problem is that of the dozen or so EDID profiles in the Extron configuration software, none of them seem right. Even the 4K60P 4:2:0 profile doesn't produce a picture and the projector says "frequency out of range".
 
Yet, if I put back the Monoprice Blackbird HDMI switcher, the projector works at 4K60P reliably. Just that the desktops go haywire whenever the input is switched, or the projector is turned on.
 
All of the cables are 4K certified Monoprice cables. The runs are 6' from NLE to switch and 15' from switch to projector.
 
Somehow, this whole technology is a lot more going on than just switching inputs.. it's doing HDCP, resolution conversion, and EDID management all in one switcher. Sometimes I think it'd be better if we had dry contact relays doing the switching.
 
As far as switchers go, I've had my fill of them. Not to mention the hassle it took to find a seller who would sell to me, as Extron won't sell to end users. I'm currently in the phase of trying to return it and get my $500 back.
 
If only I had invested $6000 in a Quadro M6000, I could probably do the EDID management in the card. But the Intensity Pro 4K experience has taught me that if I can isolate the projector to a separate graphics adapter, Windows isn't disturbed when the projector comes online.
 
I really wish nVidia would fix this problem with their multi output cards!

No, I've been using nVidia gear for about the past 20 years. I have a Titan X in there now. 
 
Black Magic Design's Decklink can do DCI 4K, but it has only SDI connections... so still looking for a decent single slot card that will do 4K 60P output. Not sure if there's anything to be gained by having a second GPU without SLI.. not sure if Adobe software will even USE the second GPU.