I don't have mine paired but am enjoying using the same OS for it's sync capabilities between the SP3 apps and my Windows phone apps. Tweetium, Nextgen Reader, Package Tracker ect. all keep the data in perfect unison between the 2 devices.
Agreed. Universal apps, contrary to bringing "crap Windows Phone" apps to tablets, enables an incredibly powerful platform for making superior apps that perform similarly but leverage all form factors, while syncing between them. Tweetium and Nextgen Reader are definitely two great examples.
Tweetium in particular works great on a phone and on the SP3--snap it to its minimum size on Windows 8.1., and it's essentially exactly the same UI, so it's very familiar. But, it can still be expanded and take advantage of a larger screen.
I think if anything is going to make Windows Phone successful (say, at least 10% market share), it'll be universal apps and the ability to make great apps that can run on so many different platforms. Seriously, once Windows 10 is running on a billion or so Windows machines (and whatever tens of millions of phones) and with very little extra work to make a Windows Phone version of an app, we'll see many, many more apps on the latter, I predict. Suddenly, the numbers will make a great deal of sense where they might not right now.