As a fan of both, I'd say they have virtually nothing meaningful in common. An interest in deconstruction perhaps, but they go after deconstructing different things in tonally wholly different ways. They're both original Sherlock Holmes stories from the same decade interested more in why he deduces rather than what, but that's a pretty superficial similarity.
I've always wondered why Nicholas Meyer's second Holmes novel, The West End Horror, was never adapted for the screen. It certainly wasn't as good a book as Seven Percent Solution, but considering the American (and probably British) appetite for all things Holmes, I'm just puzzled as to why this slipped through the cracks.
According to David Stuart Davies' excellent book Starring Sherlock Holmes, the reason was that The Seven-Per-Cent Solution was enough of a box office disappointment that it didn't justify a sequel.
You're welcome, and if you missed it tonight, don't despair -- Sundance Channel's website says it'll be airing again several times at the end of March: