For me, most of it comes down to price. That Honda conversion is cool. But expensive, and just not me. The other reverse trikes like the T Rod, and T Rex are simply out of my price range, anyway. And, the quad pictured here is very cool. But, apparently not legal here. And, again, big $$$.
The $18,000+ I am spending on my Spyder is a lot to me. But, going into the bigger $$ is out of the question.