My tablet RPM/CTR and CPC is off the hook. It's huge. It's massive.
And the reason is simple: Tablets are naturally restrictive in terms of navigating in and out of web pages, so clicking on an AD is actually more efficient than closing/opening new windows or pages (at times).
The same should in effect apply to mobile, but my sites probably aren't quite optimized enough for that to work out. Both mobile and desktop perform about equally for me.
Desktops are particularly troublesome, since desktop users are typically very adept at opening and closing web pages, and the utility of the MOUSE provides near-instant navigation away from ads, so ads present no opportunity for them to leave a web page.