I've had a cold which made me disinclined to sit in front of a computer screen for several days.
It seems that the folks at Refractions also have an open source contribution; uDig. They're based on Vancouver Island, and I've worked with them professionally. They're definitely a competent group, and recommend uDig to me. I've decided to give it my first effort because I know what they can do with other tools, and I see hints that some of the high end capabilities I was looking for may also be easy to implement from uDig and the other Refractions open source tools.