Yes, it is true because some people have a had a bag a very short time and really can't speak on how it will hold up after years of use... which I'm sure you are more concerned about rather than a few months (at least I would be). Recently a lovely friend of mine rehomes her swift K28 in Lagoon to me. This bag is (I think) about 10 years old. I don't think the bag was used very frequently (as previous owner rotated bags often) and I know it was stored in a climate controlled environment. Even after all these years the swift leather is not sagging and is in pristine condition. Bottom line is, how you take care of and store your bags when not in use makes a world of difference in how the leather ages. I keep a bag insert in the Kelly at all times when in use and store her laying down because I do not want her to sag at all.
I also had a B25 in swift and it was buttery soft. I could tell that bag would have sagged over time without proper care. I do think smaller swift bags are easier to maintain shape than larger ones. I baby my bags, especially the ones which need attention to prevent droop/sag.
Just keep that in mind if you go down the swift road =)