I have both the 70 and the 90, but I am TO. So I don't use them much. A small one works just fine. The one thing I did find nice on the 90 was it would show Permanent DTC. Maybe the others do, but the 90 shows them up pretty easy.
If you are doing HEAVY T&R Most likely don't waste the money.
Never make fun of the choices your wife makes. You were one of them.
If you want bi-directional controls, you'll have to spend 3 times as much at a legitimate dealer. You can buy cheaper from a Chinese reseller, but then you'll have to deal with the warranty via China. This is true for many of the resellers on Amazon.