I have really enjoyed reading this topic! So I'll add my 2 cents worth, even though it is late. I can't beleive that any structural engineer in Alabama would have difficulty designing based on stricter deflection limits. (My folks live there and I did for a couple of years). I think the strange look they seem to have is that they're trying to comprehend why. Deflection frequently controls design, but not because deflection will cause failure, but b/c it is a servicability criteria. Excessive defl. causes user discomfort, or poor performance of mechanical equipment. Some of the "strongest" structures are extremely flexible.