Arm numbness may be more from doing something foolish while assembling the chair, because even with a 12-hour break from the chair and a good restful sleep in there, the numbness/tingling is continuing unabated and stretching my arm in certain ways makes it go nuts. Almost sciatica-esque, except that’s always down in my legs, and the tingles are always accompanied by pain. But in any case, feels like I pinched a nerve in my elbow or something, ugh.
Back is more or less happy, though, which is what I hoped for. Longer-term reviews forthcoming to see how badly I wasted $500/how well I invested in my longterm health :)