Dennis, A lot of my interest in non-telescopic front suspensions for motorcycles dates back to the time when I was racing a Yamaha TD1, which had a fork that was telescopic in theory but not necessarily in practice. The same was true of the 750 Ducati Cycle's staff gave me in 1973.
I think pretty nearly every variation on the non-telescopic theme occurred to me back then. All but the A-arm concept have, I believe, shortcomings in varying degrees.
I rejected the forward-extending swing arm, like that recently used by Yamaha, because I believed it would limit steering lock to an unacceptible extent. By the way, I think the Yamaha design effectively has an upper wishbone.
I also considered the possibility of using track rods extending forward from the frame to the front axle. This looked promising, because the farther apart you mount the rear ends of the links the nearer you get to a conventional, pivoted steering movement. I was concerned about this because the arrangement otherwise entails a lot of mass moving sideways as the front wheel points away from center. I'm not a good enough mathematician to calculate all the effects of that movement, but in existing examples increases in steered mass tend to have bad consequences.
The sideways MacPherson strut (Kevin Cameron tells me the name was borrowed from the marching style of the Clan na MacPherson bagpipe band) employed by BMW has its good points, but the long, downward tilt of its low-mounted A-arm means it can't be fitted to most motorcycles. It fits well enough over BMW's opposed-twin engine, and I suppose you could make the A-arm straddle a V-twin, like H-Ds.
Ultimately, I think, the upper/lower A-arm design is best for the future. It's rigid, can be fit into the space available on most motorcycles, does not offend eyes accustomed to telescopic forks, gets rid of "stiction," and can provide a measure of anti-dive if that proves desirable.