The US plays them with a late mediaeval archet bow, which produces a very tinny sound. The Germans use a 1/16 violin bow, which has at least double the width and so produces a more mellow tone.
And if you want a bass one, look at the Japanese.
To some extent, the whole point of the instrument is its resonance, which means you don't realy want fast runs, for starters.
There are a mere fistful of players in the UK, although I suspect there are more around than are ever seen. Celeste Ray Howard in the States is getting some competition from the UK's Phillippa Ann Reed, for example, but as the BowedPsaltery site has pretty much been taken over by some excessively opinionated Americans, I don't know where they've got to, having left some months back.
If you want one, don't bother making one, they're pretty cheap from Thomann.
What I think Phil's talking about is an experimental model with the soundchest rotated into a vertical position, and the accidentals and main notes on opposite sides of the "side" whch has now become the "top". They are hard to hold, however, as both sides are covered in strings. The advantage is a constant distance between note and accidental, unlike the conventional BP where it decreases all the way up.