I do not remember the Lepp I. The Stroboframe Lepp II is as you mention a mounting surface for the camera, a pair of adjustable rods and 2 small ball heads at the end of the rods which are locked from the bottom as on a monopod or tripod. At times this is a bit to adjust and 4 hands would be better than 2. At the end of the rods nearest the camera mounting the rods can be adjusted on 2 axes- up, down, left, and right as well as 360 degree rotation and the ability to shorten or lengthen the rod distances between the camera and the flash heads. As you tighten the lock you can adjust the tension a bit so that the left and right adjustment is not adjusted as much as the up and down. At the far end of each rod as I mentioned there is a small ball head that is locked into position from the bottom. When released, the ball head bases can be rotated 360 degrees. Each of the tiny ball heads has a stop to keep the flash shoe from sliding out of the shoe. These tiny ball heads can then be adjusted just like any of the larger ball heads.
The Lepp II sounds like it is an improved version of the Lepp I. Adjustments certainly would be easier if first mounted on a tripod. There is a tripod thread on the unit as well. Once the adjustments are made for the camera and lens however, the system does operate well and allows one to use a main and a fill flash set up however.
Additionally, I have an older LL Rue Flash bracket made by Kirk Photo (Enterprises) which is similar to the John Shaw Butterfly Bracket. Kirk Photo and Really Rite Stuff have made improvements on this system and also include Arca type QR plates/system to the unit. For my Rue Bracket, I just added the plates to the existing bracket for mounting the camera and mounting the bracket onto a tripod.