Thanks to everyone who responded to my last post, either here or over on The Miniatures Page. It's always great to get insight from others, especially those who are also a part of the hobby.
One gent over on TMP made a very wise observation. He pointed out that the problem I have isn't 'too many miniatures' it is 'worrying about miniatures', and that if I push too hard, I may find that I have traded one set of worries for another. Being obsessed with getting rid of miniatures isn't really any better than being worried about having too many. I've already gotten rid of 85% or more of my original lead mountain, I don't need to stress about a perfect score.
So I've got a new plan. Tonight, I'm going to box up 100 of the remaining 150, put the box up in our hard to access loft and do my best to forget about it. That few, that far out of sight, will hopefully prove out of mind as well. If not, I'll get rid of them later.
With just the favourite 50 left on the work bench, I will probably find I get through them pretty quickly, and I can then return to the one-project-at-a-time approach that made me happiest.