Thus far, 100% resume from sleep. I haven't really had issues with that functionality since we got the last crop of machines (the M6400s) way back. And my older XPS 13 has been stellar in that regard. Hibernation (suspend-to-disk) is also very good.

This is probably more a function of modern kernels than hardware. My wife has had the M6400 for 8-9 years as well, but with a 3.4.xx kernel, and was having the odd (1/50?) resume failure with it. Me, with much more bleeding edge kernels, nary an issue.

With the new 9360, everything has "just worked" without tweaks, though the wifi is certainly 110% improved after the mod above. I do notice a plethora of ath10K driver changes are now queued up for the 4.21 kernel (running 4.20.0 here).

Oh, and I'm using Compiz as my window manager, spinning cubes and smart window placement and all of that. Rock solid on Ubuntu Mate 18.04. Much better than in earlier releases.

A very nice thing with the XPS 13, is that it is almost entirely Intel stuff, which is extremely well supported for Linux. And Dell themselves configure and sell it with Ubuntu pre-installed, though typically only for the most expensive all-tricked-out variant!

The only thing that I might like that's not great on Linux are the DisplayLink adapters. I have a USB2 one here, and it is indeed plug and play on the new system, but horribly slow. Not just for itself, either: it manages to cripple the entire system. That device uses a reverse-engineered clean-room driver with zero help from the manufacturer. DisplayLink themselves now have a binary blob driver for their various USB3 variants, which are reputed to work on Ubuntu 16.04 and later, but I don't have any devices with those chipsets in them.

I think the (Thunderbolt USB-C) WD15 dock is somewhere in the blizzard out there now. It might even arrive today, otherwise likely on Friday.

Cheers