I received the T100TAM today. It's a tiny bit laggier than I remember the T100TA being, but it may be at least partially due to running Windows 10 Technical Preview... that said, the new Start Menu is such a great hybrid of Win7 and Win8.1 that I don't think I could go back... I don't even feel the need for "Tablet Mode", which is good because the auto-switching isn't working with the T100TAM yet (possibly only working on the Surface line so far). The keyboard experience is far superior, even with the smaller island keys, thanks to the longer key throw. When detached, use as a tablet is infinitely more enjoyable than the Surface pro thanks to the reduced thickness, weight, and rolled edges.
My only other complaint is charge speed, so I may end up getting the 3.5A PWR+ Charger depending on if it's an issue when traveling (going to give my old 3.4A dual-usb charger a try first).