Just out of interest because you seem like you might know - does Windows across devices do a good job with audio latency? Presumably Windows as a desktop OS has it down, does that carry to phones and tablets too?

As eropple covered quite well, native Windows latency isn't up to industry standards. ASIO4ALL has been very good to me on the desktop OS, but I believe that is very RAM dependent - I've never run it on less than an i5 with 8GB of RAM, whether XP, Win7 or Win10. Because it's free and community supported, I consider it simply an oversight by MS.

Unfortunately I can't speak to Windows phones or tablets, because I'll admit that I've used iOS for that. There's simply too many good, well, excellent audio programs in that sector to try otherwise. My main ones are Propellerhead Figure, GarageBand, a few synths in production, and djay2 for fun playing tunes and mixing.

The issue that Windows can address with the tablets (not sure about phones) is the ability to plug in a USB soundcard. This is an extremely helpful ability that iOS really doesn't support (again, the native CoreAudio deserves recognition as very good). I got a very small M-Audio (now owned by Avid) soundcard that runs ASIO drivers, has a mic in and phones out (both stereo), and I even got an Asus Netbook with 2GB of RAM to run Ableton Live 8 well enough to create loop-based tracks on the go! For live performance, people simply love the MacBook Pro platform because of stability, and I can understand. The more that Microsoft does though, the more attention that will be granted from software developers to try and capitalize on the potential market. If MS continues to keep their hardware/software combination friendly to more tech savvy type musicians, e.g. plugging in a soundcard and running desktop type software on portable hardware, then I think they'll be able to take some market share.

I do have access to a Surface Pro 3, but because I'm happy and still working on my Lenovo ultrabook with Win10 (keeping my prior Win7 one as a 'desktop'), I'm not really anxious to go messing with that. But, for DJ type folks who use 'controllers' like the stuff made by Pioneer, a Surface Pro plus a controller with built-in audio is a compelling offering. Not cheap, but not a toy either!

Windows still trails OS X and Core Audio here unless you're using ASIO. There are no real ASIO drivers (AFAIK) for the Surface Pro 3, though ASIO4ALL works if you want to dedicate your sound card to just ASIO apps (for me that sucks, because I want to hear other audio on my system at the same time!). With my Macs, though, it pretty much just works. I'd probably use an external interface if I absolutely had to use Windows (and I'd want a bigger screen than the Surface Pro, probably the Surface Book and even that's cramped).

Gotta say you really did hit the nail on the head with this comment. I'd like to mention though that I've been using 12" screen gear for about 5 years now, both in production and performance (DJ) environments, and I've yet to really run into issues. Granted, I've had an external monitor or a projector going from time to time, but, like when running Line6 Gearbox, I'm not looking at the screen nearly at all. When running Traktor Pro, I try not to look at the screen very much as well, because looking like I'm "checking my email" is a constant dig at folks who use laptops as performance platforms. I don't mention these as contradictions to your perspective, just another few thoughts to consider!

On the (sadly rare) occasion I get to play with music stuff these days, I really have trouble going away from my 2x1440p+rMBP 15 screen space. Even just the rMBP is super cramped. Different strokes, I guess.

Ableton seems pretty good lately on Surface Pro 3 + Windows 8, and I don't find it sluggish or buggy, but there is some latency with audio recording on the built-in card. I haven't tried using an external audio interface (which are incredibly cheap these days).