Soft proofing

[Hamster]

Until I get a full 10bit system and workflow .. can't even begin to help solve something like that.
Have you downloaded the 10bit test ramp file?
This should help you determine just how 10bit(ie. aRGB) your computer is.

Re screens, I'm pretty similar to you on this. Other things pushing me away from Dell is that I can't seem to easily find out about the software development kit that is used for calibration, plus I would need to spend $300 on an i1pro calibrator from x-rite (as the colormunki display I have isn't supported)...

Had a quick peek at imagescience the other day and they have a reasonably priced NEC screen for about $2.5K. It's not what I'd prefer(a 4K 10 bit 30" screen!) .. but anyhow ...

Re the Dell screens: any calibrator will work on those screens without any issue. Where the iPro is handy to have is that it can 'hardware' calibrate the screen, so it's independent of any software to load the LUT into the VGA card.
This is supposed to be ideal in a few ways, but not really a necessity!
I think the major advantages are that you don't have cluttering software to set the screen calibration during bootup into the OS .. both time and resource usage here.
You can effectively use that screen on any uncalibrated other computer and know that the screen is still well calibrated .. etc.

I wouldn't discount the Dell solely on that basis anyhow .. I'd probably plan it so that at some point in the future, getting the iPro calibrator will help .. but you wouldn't be limited with what you have now.

Speaking of which, I have a Spyder 3, and while I know many folks(here and elsewhere) are more than happy to run the Spyder software, on my PC it was flaky, dodgy, unstable, unreliable, miserable, and I think in the end inaccurate. In the end I trialled and then purchased BasICColor for calirating my screen. Does a good job, is almost instantaneous and seamless in loading the calibrated rendering. On Win10 tho it does now take a sec or two to finally load up, where on Win7 it was loaded before the desktop started to respond.
But I actually prefer the way it now works on Win10, as I know the LUT is being loaded up.
The only reason I use a desktop image is to view some of my (known) images as a sort of reference point in terms of calibration points.(Otherwise I hate them(desktops with distracting images).
On Win7, you had to assume that the calibration software was doing its thing. You never got to see the screen rendering change which basically confirms calibration.
But now that the LUT is being loaded just after the desktop settles(so an image is on screen) .. I now see it go from a looking image of horrendous proportion, to what it's supposed to look like

Out of gamut warnings .. can't really offer any advice or help .. as in I have no experience with it.

While you say that your computer is 10bit compliant, I've been reading up on the topic and there is a fair amount of conflicting info about whether there is or isn't.
It's not as clear cut as there is, or there is not!
Even tho some nvidia cards are 10bit capable, they aren't all of the time, and in some instances a true 10bit capable VGA card is needed(eg. an nvidia Quadro card or similar).
But I know even less than nothing about the Apple world of hardware software and where to search for reliable info about the environments they create.

eg. (in a Windows environment) You can have a 10 bit capable nvidia GT750 card But apparently many applications(Adobe's included) don't actually use 10bit mode with any VGA card(even tho it's 10 bit capable, and set in this way, because of the way the software's API is written. Nvidia's website has a bit of info about it.
And also, you may have a 10 bit capable card, and 10 bit capable software, but if you run Win7 with the normal Aero theme(the default), 10 bit mode is disabled.

A lot of the info found is a bit old, not much between '14 and '15, so maybe al the modern(new) graphics cards/chips now run 10 bit without restriction?
Maybe Win 8 to Win10(for us Win .. gers!) runs natively without restriction in 10 bit mode too?
You'd kind'a hope that these software-hardware conflicts are slowly becoming a thing of the past.

no, I'm still to download that file, but I'm guessing that since I only have an sRGB screen I may be limited in what I see.

Thats a good point re the calibration. Agreed I can software calibrate, but I was thinking I'd hardware calibrate, hence the ref to the i1 pro. I've been looking at the cs270 at about $2k as the Nec seemed to work out slightly more by the time I'd bought Spectraview (can't remember if I needed a different calibrator too). I'll have another go to see how Mac compatible and easy the hardware calibration of an ultra sharp is.

I haven't delved too deeply in to 10 bit capabilities, just noted the link in a previous post, which contradicts what Apple Store staff said. Not too worried about it really given all the Mac using pros that have been managing fine without it for years. By the time that software conflict disappears, no doubt there'll be a new generation of conflicts