I find that keeping my basha rolled up for extended periods is no problem at all, so long as it's completely dry.
When you think about all of these things, they spend months and even years tightly packed in the bag they barely go back in to at military stores and then shops before you buy them. If they self destructed after being stored this way, you'd never be able to use even a "new" one.
Same goes for down jackets and about anything else you are to mention, just make sure it's dry and clean and appreciate all the free space you have by packing it up tightly.
Joe