The time skip feels natural, and even though I was initially skeptical about the premise that Hank and Peggy moved to Saudi Arabia for years (seems so out of character for them), I now appreciate how it allows us to see the Hills react to the ways life in the US has changed. It was a great choice.
My head cannon is the smoking illegal pesticide chemicals have caught up with him and that's why he sounds a bit different.
Kahn on the other hand... That's not Kahn, He's erratic and higher pitched.
Overall I loved it tho, this isn't a reboot, this is just turning back in a bit later down the track. It's gonna be fun going from season 13 to 14 in my next run through.