Take a look at all the 1-star reviews for this product. You will find that almost all of them are related to the size 3 version of Swaddlers Sensitive. Unfortunately my experience has proved the same --- the size 3 versions of these diapers are indeed (for whatever reason) different than the size N through 2 of this diaper.
My daughter has been in Swaddlers Sensitive since she was born (started in size newborn). They have been great diapers for her --- rare blowouts, rare diapers rashes, and if she did have a rash it was usually easily remedied by moving up to a larger size.
This all changed when we started her on Size 3 of the sensitive swaddlers. First, I found I was changing her more frequently (or at least checking her diaper more frequently) because of a horrible chemical smell coming from her diaper region. I thought it was just me --- but reading reviews here confirms that it is the diaper. For some reason, the size 3 versions emit this horrible chemical smell whenever the diaper becomes soiled with urine. Some reviewers have suspected that this is because the size 3 versions actually contain Pampers "Dry-max" chemicals. This may or may not be true, but what i do know is that something is definitely different about the size 3s versus the N-2 sizes.
Second, my daughter developed a persistant rash once we started her on the size 3s. Since she had been in this type of diaper since birth, i thought maybe it was her diaper cream (we use aquaphor). We changed that to Motherlove diaper cream and the rash still persisted. The pediatrician also prescribed her some anti-fungal (nystatin) cream in case what she had was something worse than a regular diaper rash. Still no improvement. Finally we changed her diapers (to Earth's Best TenderCare diapers, size 3). Within 1 day, her rash improved and now a few days later it is completely gone. This suggests to me that it was indeed her Size 3 swaddlers that were giving her a problem.
Finally, as other reviewers have noted as well, the size 3 diapers just FEEL different as well. They are thinner, not as soft, and overall feel cheaper than the size 2 versions.
Bottom line -- i truly believe there is something very different in the way the Size 3 diapers are constructed. If your baby is moving up to size 3, go ahead and try these --- but just keep an eye out for any reactions and have a set of another type of diaper on hand just in case. Good luck everyone!