One additional convenience of a trailer is putting it on just about any bike. I used my Wike on my recumbent for years, and now on my Gunnar (Waterford) thin-walled road bike. My friend used his BOB on his carbon Trek Madone for years. These trailers attach to the rear axle, so no stress on the bike frame - the two-wheelers can actually be packed balanced front to back so also no weight on the axle! Agree with aforementioned shopping convenience with trailers: last summer I even bought a BOB bag for my Wike, increasing capacity. I can bungee shopping bags on top when near campgrounds and getting dinner groceries. Same experience as above with easy firewood packing at camp.
I also agree with the analysis of the BOB proneness to shaking which I've called tail whipping. I had no control at all, it's not even like a bike shimmy you can control with knee on the top tube, it's totally scary and you will go down. On the other hand, obviously BOBs and other single wheelers are used for millions of miles without issue, so it may be the flukes that take us down. I'm convinced the BOB that took me down had an un-parallel frame that made it inherently unstable, and paired with the poor loading there the wipe out was inevitable. Weirdly, the long story on my using the BOB involved lending my Wike to my friend and taking the BOB as he was unstable on his old but newly purchased Cannondale recumbent with the BOB. He also couldn't keep up with us. I took his BOB, then took more weight off the Wike onto the BOB to help him. Ironically, this was my downfall!
Lastly, the BOB does track right behind the bike better than the Wike, and one wheel is less friction than two. This convinced me to re-try the BOB on a recent tour with my Gunnar (upright bike, not recumbent), but the BOB took much more concentration to keep balanced, while the Wike is super-stable and forgettable. I won't go back to single-wheeled again.
