Fellows,
I'll preface my comments that I'm pretty sure a highly skilled craftsman could build a viable teardrop out of duct tape and soda straws

And so if the need strikes you to experiment with corrugated siding, I say full steam ahead! ...
... with that said, I think it does pose several challenges, especially when used on a traditional teardrop shape like a Benroy. None that can't be overcome, but challenges nonetheless. MC has overcome them very elegantly.
1. Corrugated panels get all their strength from the rib pattern. The metal itself is extremely thin - about half of the 0.040-inch teardrop standard. That means less strength and hail resistance. Also, I wonder how much that rib pattern is going to affect fuel efficiency ... it might have a pretty large effect if the ribs are oriented perpendicularly to the airflow.
2. Now, mainstream travel trailer manufacturers have been using corrugated siding for years. However, most have had difficult adequately waterproofing the overlap S-lock seams, fenestration openings and roof corner seams. Higher-quality manufacturers have expanded into using closed-cell foams, I think. Cheaper ones just use gobs of putty tape, which may shrink and crack as years go by.
3. I know Frank Bear of Vintage Technologies uses corrugated siding for the sidewalls (not the roof, though). I think it's aluminum, but you'd have to confirm ...
P.S. Bushido41, if you have a semi-truck manufacturer in your area, they have giant rolls of aluminum up to 8'-6" wide. You might be able to snag some.