Brazilian coffee bean research institute found three coffee plants with very low caffeine levels. Currently they are 4 years away from supplying a natural coffee bean to the market.

What I'd like to know is how these very low caffeine coffee beans taste in the cup.

We already have eugenoides and laurina, which are low caffeine varieties. They are generally very sweet, low in bitterness and fairly low in acidity. Sometimes people describe them as having like an artificial sweetener type quality. Of course, they are scarce and thus fairly expensive. I don't know about yield and disease resistance, but it would surprise me if there weren't a commercial market for them if there were greater availability.