What cost progress?
I jest. I've got two Anthem X 26" rear triangles. One from my 2010 Anthem and one from a 2011 (or 2012) SL1 Anthem.
2010 rear triangle
This triangle features an IS brake mount and I've currently got it set up with a PM 140mm brake adapter and two Ti bolts holding it on. All up, with bearings and derailleur hanger in place it weighs 685g. Without the brake adapter and two bolts it'll be about 660g.
2011 (2012?) rear triangle
This triangle features a PM brake mount for 160mm brake rotors. All up, with bearings and derailleur hanger in place it weighs 700g. The "seatstay" tubing seems thicker and of a more angular profile. Perhaps this is where the additional weight comes from. It's odd that they ended making the later Anthem X frames heavier than the earlier ones. I could understand if they beefed up the front triangle, but those 2011+ year Anthems were prone to cracking at the seattube/toptube junction which they made extra thin on the 2011+ Anthems.