To answer a few of your questions:
No testing so far. I am making a table and fence extension that should be about three feet long. I wasn't planing to sell them or draw up plans but if anyone is interested I could provide more pictures and answer questions. It really wasn't very hard to make. I just used stuff laying around to build it. I don't know how well the wood block will hold up but it should be ok. It's oak with the end grain up. The left table section slides back and forth a small amount and is tightened down by two nuts so the wood cutting block can be firmly held in place. Even with a split block it doesn't matter because it doesn't have anywhere to go.
It's not ever going to replace a knife. It is made for repetitive work and there is a clamp on stop to speed things up. The time it saves is more in the measuring than in the cutting.
