I am getting ready to pre order a incase gig bag. I usually bring only one bass to gigs, however there are times when I bring a back up. Would it be practical to buy a dub bag rather than a slim and only use it for one bass most of the time? Does the bag need to have two basses in it to keep the basses from moving around? I would rather spend $300 for one than $400 for two, but if the dub is inpractical for transporting only one, I guess I'll have to bite the bullet and get two. Anyone have experience with this situation?