My bows stay in the house where they won't undergo temperature extremes for long periods of time. Not sure how important that is in the grand scheme of things but I guess I look at it as "better safe than sorry" thing.
I wouldn't trust a soft case that could expose the sight, rest, string and cams to damage during a drive to hunting camp so I've only had the hard plano-type cases. I think an exceptionally stout hard case like Smoke is speaking of would be important for airline travel (and even then I'd be really concerned about how the bow would fare while the luggage loaders sling it around to see how far they can throw it).