I could be wrong but i doubt most bikes would survive undamaged loaded with 50lbs of groceries, solid tires, and an accidental drop into a pothole.
Maybe a BD or Yuba could take it, but why would you want to put that kinda stress on your $$ cargo?
Me I prefer fat tubes+fat tires...on big-rigs, tire suspension becomes really important when loaded to the max...the cargo/truck+driver would'nt last long without it.