I haven't tried A5 Wagyu but I've eaten lot of really expensive Hanwoo beef in Korea. Hanwoo doesn't have the crazy Wagyu marbling but still way more than USDA Prime. And I have similar thought as you about good CAB ribeye tasting just as good if cooked properly as any Hanwoo or Wagyu. It's why I didn't order that A5 Wagyu ribeye from Crowdcow during the sale even though I was tempted to check off the bucket list. If I'm going to try A5 Wagyu for the first time, I want to do it when I visit Japan so I can get the full experience.
I am not trying to discourage anyone from trying it though. It is very good, and I think you should try as much food as possible.