This is a very common phenomenon for Gifted Families who start homeschooling. Lots of them plan on a very laid back start 'deschooling' I believe it's called, where there is no plan and no pressure to do anything 'school.' Obviously you are going to want to leave a very 'Almanacs' around, and plan a few trips to the library and field trips, but it may take several months of 'no school' for your son to rediscover that he does actually love to learn. This also has the advantage of giving you plenty of time to observe your son's learning style, favorite topics, talk to him about what he his interest are, and collect possible resources/materials for when you do start schooling again.
Doesn't that sound cool?
Grinity
Yep, sure does.
I think we've arrived at our decision and are looking forward to it. I was telling someone yesterday that a great deal of my DSs school experience is akin to being stuck in traffic at a green light. He's ready to move forward, yet can't because he's in a class with 20 or so other kids. It's a situation that can't be helped because he's not necessarily ready to advance another grade, but he'd like to move at a faster pace and that's just not always possible for teachers/schools to accomodate. So, it seems the best alternative to personalize the experience and provide what he needs is to HS. There are other factors, of course, but this one is a big concern for DS.
Many thanks to everyone for your input, it's greatly appreciated. I'm sure I'll be back as I progress to curriculum selection and so on.