The following is just me throwing out thoughts not a disagreement: When I said very large boomerang I was just using that as an example of a curved or irregular surface. Think 15 foot boomerang shaped object. The pass through might be able to handle it but the S/W will have no way to determine whether the rest of the object is straight, curved or jagged. Alignment to the object becomes impossible. There has been a lot of discussion about automatic alignment to materials but as far as I can determine all of the company responses were about materials that could be imaged as a whole, like the Macbook or materials with deterministic shapes.
This response from dan was not about the pass through but the far easier condition of an object wholly within the Basic.
All of the academics aside… I can easily see why someone would want to etch a pattern on an 8 ft board and the registration issues you have discussed are easily handled. The effect is also something that is difficult to do in other ways. But trying to make a 25 ft banner in greyscale is not something that I personally would consider visually striking or cost effective, and would take a long long time.