I have the first double lever guitar that Jackson’s made. If you have any specific questions I will be glad to answer them. The way I currently have my guitar set up: G#, E, B to C#, G# to A, F#, E, D, C#. I have talked to Jackson’s and they are willing add a knee lever that will raise and lower the high E string down to D# and up to F#. That will complete the tuning. It’s a great guitar I can have pedal steel that I can take some where and just play.
I have an old OMI Dobro with the "Edge for Resonator" installed. It's a single lever at the wrist, that changes multiple strings. In my case - D A D F# A D to D B D G B D. It's an "all or nothing" move, but with some careful blocking and a few behind the bar string pulls I've been able to do some fairly reasonable melodic work with it. The system is surprisingly accurate and stable, once I got the changes tuned in.
The Edge can move several strings in either direction with some caveats. The tension has to be at a certain level to allow the lever to be played easily. There also needs to be some experimentation with string gauges. I originally had my guitar set up to go to a full A13 chord E, B, G#, F#, E, D B E. The back lever moved the high B to C# for a C# minor. While the front lever raised the G# to A, lowered the D to C# and low B to A and raised the low E to G. I haven't had any string breakage but I was told that the high G# to A pull wasn't possible.
The big advantage of the wrist lever is that it does allow fairly normal blocking. The one issue can be the low strings there isn't that much room to set the hand down which isn't a problem for finger blocking. Even if you play a six string tuning, I would still recommend buying an eight string model and having the meat of your tuning on the top 6 strings.
Looking at the price, why not just buy a pedal steel? I like the technology, but most of these devices seem very awkward to use and pretty limited. A knee lever would be better. I guess it would be pretty cool on a dobro.
Tim, I agree that most of the lever benders are a bit awkward to use, but the Jackson system looks the least awkward. A large part of the appeal, for me at least, is the simplicity and portability of such a guitar. Does seem a bit pricey, though. I think their 6-string pedal steel isn't much more than this lap steel model.