It's a hard move from a Golf R. I watched a video in my travels and the classed it as the best hot hatch in the world ever.
It's hard to disagree with. My partner wasnt sold on the R, I tried, but she was sold on the A35 in minutes. I would have had an R a long time ago if it was MY choice.
The Golf R by nature/design is more of a Q car, understated and subtle in its intent, thats the attraction to many, including myself, but of course others simply seek more visual intent and thats where the Ford RS and the Honda Type R fills its orders and now there is the somewhere in between I think with the A35 (with Aerodynamic kit) and can certainly see why the wife would be attracted to the A35 over the Golf R and no judgement here as I obviously like the AMG enough to seriously consider it as an alternative over such a great car as the Golf R.
My wife likes her cars also, was quite specific on what she wanted (this was bought mainly so can have my R back, as her Mini Cooper was feeling quite unloved!)when we sourced an A1 Black Edition 185 BHP Mythos Black (2 Door) so she has an appreciation for cars and she liked the Mercedes also, but her concern was the spoiler as "its a bit too much" and she said if pushed she would stay with the R - So she also loves the R, often gets some young lad with a noisy exhaust make himself known and she usually leaves that person looking at the 4 pipes (love my wife, takes no sh*t

But digress! 2 great cars, there is no real loss in which way you choose, just have so much love for the R it would be hard to part and decided to take that love affair on 3 more years. Truly feel its set the curve in this sector and these cars might actually be some of the last great ones as electric, semi and autonomous take over the world.