Multi-scale guitars have been out of patent for years now. And if the harpejji was invented in 2007, then I believe it should go out of patents next year? I hope the resulting competition makes them up their game.
I've worked on my own instruments many many years ago (with a little help from a professional luthier). I'd say if you're designing a new instrument, multi-scale should be a consideration; even if it's just a plain old boring guitar, your biggest constraint is the choice of a bridge.
Glad to hear Strandbergs are nice... I'm sorely tempted by one.
This tapping instrument seems very nice but certainly not bizarre, if you want bizarre, look under a d10 pedal steel. If i were to buy a tapping guitar, I would also look at Markus Reuters, touchguitars.com.
Patent lifetimes are at least 20 years after the filing date as per TRIPS treaty. There's the priority mechanism for international filing, providing up to another year, and there are usually various means for additional protection time if regulations delayed the process. Those are mostly relevant for medical patents to compensate for trial-based delays, but "the PTO was too slow" seems to be reasonable ground for an extension, too.
As such, we're looking at 2028.
I was wondering what you could mean: in the US, before ~1997 patents used to be valid 17 years from the date of patent grant, which would fit the timeframe you mention. Grant date was usually a few years down the road and with submarine patents (keeping them in limbo by continually sending minor changes to the USPTO until it's worth having them active), that span could be extended practically infinitely. That time is, thankfully, over.