I think I'll take a close look at it.

As for suggestions, I see that it has dependant parameters but not mutually-exclusive parameters.

I wanted to get some replies before I put any effort into re-inventing anything, but my musings indicate that some possible features can be order-dependant, which is a problem with the use of a hash for a prototype. I'm also worried about slowing it down if it's too fancy!

—John