I have ridden a 'bent once. An old GF's parents had a neighbor who had one and thought they were the absolute best thing ever. They lived just west of the Rose Bowl in Pasadena CA.
The neighbor insisted I ride his bent, so I did... I tried to climb one of the 20% grade hills. I routinely rode my Peugeot CFX-10 up those hills, but I couldn't make that 'bent climb them. And not so good coming down, either.
And please no stupid comments about needing different muscle groups. At the time I ran and lifted weights regularly. 'Bents are the ultimate expression of trading aerodynamic shape for weight.
So I'll add another situation where 'bents suck: extremely steep hills.