I have only briefly looked at some of those options (I checked out Wilson Hill Academy over the weekend after seeing you had recommended it to someone else), but I'll look at the Well Trained Mind discussion at some point. Thank you for the reference.
My general outlook at this point is that I'd prefer to not sign up and pay for another year of CC, though there are a host of x factors related to that which I won't get into now. I'd like to cobble together a curriculum, pulling from an assortment of resources and tailoring things to our teaching strengths, our son's learning preferences, etc. If we choose this approach going forward, I could certainly see using an online class for HS science. I've also heard of homeschooled students taking community college courses.
Those decisions are a few years away, but I think my wife is reticent to take that path because anything other that the "one stop shop" would feel too complicated for her. That's what I was trying to explain in the "Finally..." paragraph above. I think her fears regarding leaving CC are primarily about losing some wonderful friendships (for her and our son) and about taking on the extra work of developing and supervising a customized curriculum for our son.
I've gathered that some have stuck with CC but done their own thing for science or perhaps some other subjects. According to the official verbiage from CC, this should be absolutely fine, but I really don't see this being a workable solution for us either.
Perhaps if my wife and I come to a place of some accord in how we think about science education, the way forward will become more clear.
p.s. - I realize I've put this conversation far afield of the original topic. If you feel it appropriate to split the conversation off, I'll understand.