DC Amore are thinner. They're about on par wth Bambino, probably made on the same machine. Princess are a reskin of Safari and are presently "as thick as it gets". Seriously, if she's lamenting about the amore being too thin, you really have to get her a bag of princess and watch her try to deal with the waddle!!
I'm also quite jealous of your luck in having such an interested GF, don't let that one go! I'd absolutely love the opportunity to pamper my GF in a thick princess diaper!
I have both the 2015 and 2016 versions of the amor and I also have some princess. The 2015 amors I think were better than the new 2016's except for the tapes. The 2015 had smaller tapes and the 2016 had larger tapes but they screwed up by not compressing the SAP to make the diaper seem thicker. By doing so it is initially thicker but the SAP just comes loose and goes all over the place inside the diaper leaving clumps and what not all over the place. After a few hours of wearing you'll need to change because they start to get uncomfortable with all that matted up padding everywhere.
The princess is way better and thicker with a softer outer shell than the amors. If someone would make a rearz safari or princess with the DC amor print it would be the cutest best estate diaper ever lol.
I think you're referring to the "anime" print when you say 2015, and the "kittens" print for 2016? I didn't notice a change in tape sizes, but I didn't really look that closely at the anime ones. Most people agree the new kitten print is a lot better looking.
Although I can respect the princess print for its good design, it looks to me like it's going a bit overboard on the color. The safari are a full-shell print too but there's a good deal of whitespace between the animals so that tempers the color a bit. I'd suggest they drop the pink background and just keep all the characters and designs, but I suspect a lot of people prefer them FOR their all-pink background. And we've got quite a few white shell diapers, the people interested in pink deserve some love too. All they have are the kitten and the princess.
The DC amors had two runs of the kitten and puppy print after the initial anime ones. I didn't find out about them until after the anime print went out of production. The first run had smaller tapes and was a much lighter shell than the newer run which made the diapers a deeper pink with larger tapes. Overall they were good changes except the change in the compression of the sap making the new run seem thicker but also having the issue of the "stuffing" going everywhere after a few hours of wearing them.
*edit* There's actually a few comparison pictures on their website so you can see the difference.
I tried the DC Idyl diaper which is the blue version of the Amor diaper. They are pure garbage; don't waste your money on them. The tapes did not hold at first, then they popped and tore the diaper I was wearing. It is not a very well designed diaper. If you want a good diaper, I would go with anything by Bambinos or the ABU Little Pawz or Simple diaper. But if you like anything close to Pampers (as most of us ABDLs do) I would recommend the Super Dry Kids or Cushies diaper or the lavender one if you want a girlish print.