Single-action lever harps

I remain enormously curious about these:

Douglas/Dilling Harps

They are a type of lever harp that is actually a single-action beast, with only seven levers — reachable by either hand — along the top of the harp that change all strings of a given pitch class, much like a pedal does on a pedal harp. The creator is working on a double-action mechanism as well.

I must say that I would commit crimes to own a 40-string double-action lever harp. I really do not understand why this mechanism isn’t standard on all lever harps. This seems to be to be a big failing in the harp world, where lever harps are made by and for people who are either not interested in the more complex (relative to lever harps) mechanism, and pedal harps are made by and for people who are not interested in the fact that the lesser complexity (relative to pedal harps) of the mechanism makes it a far less expensive middle ground between lever and pedal.

This is a cultural failing, in other words — and a great shame. Most harp manufacturers who are able to do this (the big names) do not want a more affordable middle ground. If you want to do more than $2000 will allow you to do, they want you to have to pay $20,000. 😦

I may want to get one if it has a good reputation as being robust and not requiring much regulation; I don’t trust a typical harp technician to know how to maintain it or even to want to go near it. I’m also interested to learn what kind of strings work best on it.