After a very short learning curve with version 1, I came to really enjoy using a shoulder stock. I guess they are midway between hand-holding and shooting on a tripod. You cant get past a tripod for stability though, so the solution was a stock with a quick release base, so it could be fitted to a tripod for the slow stuff or unclipped for flight shots. This is version two - I love it.
I'm really surprised they are not more popular. They seem to be one of those things which has been around for years and never really gained acceptance but never really been killed off either. I do notice that they become very top heavy with a large lens though, so maybe that is the limiting factor. Maybe the lens you see on it (Nikkor 300mm f/4) is their limit.
Please try to ignore the pile of weeds we so optimistically call a garden.