While you cannot tent the KeyMouse, not having to constantly switch between keyboard and mouse hundreds or thousands of times a day is a much bigger ergonomic plus than simply tilting the two halves a few degrees. Also, being able to use the two halves as far apart as you want greatly mitigates the need for tenting.
The KeyMouse DOES have an adjustable hand rest (and a lot more I didn't mention). If you watched the Kickstarter video you'd know. I did provide a link to the campaign.
Of course there's a market for it. It consists of everyone who is tired of constantly switching between keyboard and mouse, not to mention all the other fields mentioned in the campaign, in other words, the exact opposite of a niche market. People just never thought an alternative existed until now.
Not sure why you're wishing me good luck since I don't think I'll have much difficulty buying a KeyMouse when it is available, though there is always a chance they might be sold out really quickly so there's that.
Trackball edition is planned but no definitive timetable until after the core product is finished.