I have a 1-piece blacktail and have shot Dave's demo Schafer. I also have another blacktail (Snakebit TD) on order and a Schafer Silvertip on order also. So, you can see I wasn't able to compare and eliminate one.
As others have written, both are fantastic bows. The blacktail is simply beautiful and better made than the finest rifle; fit, finish, joints, wood grain, etc. I had to have some help with the blacktail to tame its "twang" but Night Wing solved that for me--brace height tweaking. The checkered grip on the Blacktail is the first checkered I've ever felt and I love it. The grip on the blacktail is more compact than the Silvertip and makes you set your bowhand correctly which is a plus in my book.
When I received the demo Silvertip I was immediately impressed with its "heft" and "killer feel". Sorry I can't explain this but the Schafer just felt like it was made to hunt. Maybe its because I know of Paul Schafer's reputation as a bowhunters hunter? The silvertip is also a perfectly built bow and I'm expecting mine to be very beautiful. If you want FF you have to use Dymondwood in the Schafer riser (with an exotic wood flare if you want) and that limits you a bit on wood choices.
You can't go wrong with either bow. However, like BJ said, if you can try one out, the $50 in shipping (to and from) would be well worth the investment if you want to buy only one. Both bows have similar build times -- 10-13 months. The Schafer requires a 50% deposit and the Blacktail $100-150. Both bowyers are immensly helpful and patient as you decide exactly what you want in the way of woods, checkering, etc.