Hard question...right up there with my other hard questions...
How deep is a hole?
How long is a piece of rope?
How much wood would a woodchuck chuck if a woodchuck could chuck wood?
Seriously I reckon it is worth a bit of effort for something that you enjoy and get satisfaction from...4 hours or so is not really that much in the big scheme of things...
Heck, in spite of likley poor weather I'm still going to get the boys up early and drag them down to the Sydney Observatory...even if we can't see the transit there will at least be coffee and donuts (or muffins)...
and an interesting story for them to tell about what a nut their good' ol Dad is!