I bet there is almost zero chance of this not getting out of hand. Just to be different, I'll offer something a smart fellow once told me: the difference between a feature and a benefit. A copy machine salesman was extolling the virtues of his company's latest product. After painstakingly detaling all of the benefits of the new unit, including the heavy duty wheels to facilitate moving the equipment around; he was informed by the buyer that the wheels might be worth something to somebody but he sure wasn't paying more for them because he needed a stationary machine. A benefit's nothing more than a feature if you don't use it.
Since you're going to change your oil at 50 hrs regardless, many of the benefits of a full synthetic just aren't going to matter to you. That's OK - personal choice.
The blend is a compromise product. It's a mixture whose cost, quality, performance, etc. will fall between a natural (that sure sounds like a funny way to refer to it!) and synthetic. One of the big advantages of a full synthetic is it's great VI. This isn't much of a benefit if your climate doesn't change or if you use different oils in summer and winter. A blend will not have a VI as high as a full synthetic, it will be higher than the 'natural'. I think you can pick any parameter of the natural, full synthetic, and blend and go through a similar compromise discussion.
This includes cost. I think you can figure out about how much of the blend is synthetic by looking at the cost of a comparable 'natural' and full synthetic. I work for a company that distributes a complete line of synthetic and blend industrial fluids (it's not our primary product, but since our products use them and we have a worldwide salesforce we're a logical distribution channel). We don't really make much more money on 5 gal bucket of a full synthetic than the blend (for you accountants, the gross margins are comparable). I would guess most outfits that carry a full product line would have the same situation.