Wow, such a great discussion of the evolution of competence that I feel comfortable sharing my own lessons. So, in a mind dump and hopefully roughly chronological on the learning curve.
1. Do not try to learn by leaning back at the start. Sit up and let your muscle memory of riding a tricycle connect. Actually its a lot like a Big Wheel that way and, then, once you are pedaling smoothly lean back into the seat. This is likely true for any model, but especially for older Silvio 3.0 and Vendettas.
2. Learn without clips. If you have a lot of experience with clips, you will quickly feel naked without them and, once you get clipped in, everything changes for the better.
3. Yes, learn on empty roads and parking lots. The only access roads out of our 'hood are narrow two lane country roads (with heavy traffic as development has encroached onto the countryside) with either 3% or 5% grades. It was only this week I finally felt sufficiently non-wobbly and in control to ride out of my driveway and tackle those climbs without any concern I would hold a steady line with passing traffic.
4. Cautioned that a lot more glute muscle is involved, I learned these bikes require a lot of core strength and stability, especially for climbing. Get off the bike and integrate in real strength and core work. Happy to share the portfolio of exercises I have evolved through (working with a professional therapist and coach is an indulgence but was necessary for me, but happy to share what I was given).
5. Yes riding a fog line is possible, but someone else posted a key technique issue for stability--higher spinning cadence than on a DF. Your front wheel and front crank, more than on a DF, are like gyroscopes. The faster they spin, the more stable they are. What happens is that, as you spin faster, your legs begin to be the controlling balancing force, not tugs and pulls on the handlebars. The result is much, much smoother lines. On climbing that also means shifting up more than you might on a DF to really spin up-once that is figured out, the climbs and the fog lines come together nicely.
6. I actually do feel comfortable in a pace line where you can have trust in the riders ahead, no less than on a regular DF. What is tricky is remembering your crank is the most forward part of your equipment--especially important if you are cruising along in your small ring and have the teeth of the big ring exposed. Yesterday, I joined a group that did 45 miles and though we were not pace-lining, it seemed we were all comfortable with me in the line, and also on the front.
7. Wobbling is, I think, a consequence of all of the preceding not being mastered. This is my second full summer on a cruzbike, having no prior recumbent experience, and my wife often drives SAG on my long efforts. She is the best witness and states nearly every time how different I now look on the road. Which also means I am more efficient, which means energy is going into the pedals rather than correcting wobbles.
8. The neat thing about the core work is that, on a climb, it also allows you to sit up and shift your hips slightly back (on my Silvio). That opens up your IT band and hip flexors a bit and also enables the spinning better on the climbs.
The results of all of this, halfway through my second year on my Silvio--logging 125-175 miles a week, comfortably nearing or exceeding 20 mph on the flats (with low power output) and often doing steady climbs up to 7% in my big ring. Last week, I even climbed my nemesis--a 300 meter climb at 14%!
Good luck to everyone.