Yes - I switched from the 1st gen 12.9 to the 10.5 with Smart Keyboard and LOVE LOVE LOVE it!
Typing on it now on the kitchen table, it's so sexy and portable, and it does one thing that I always loved about the iPad and had kinda lost with the 12.9":
It doesnt feel like working with a computer - it's more like using a sketchbook or something. Hard to describe why so, but it's really liberating.
Still I'm secretly dreaming of ALSO having the 12.9" but cant really justify it. I'm gonna wait till iOS 11 drops and maybe will get a 12.9 on eBay at the time.