Weight of SRAM PG1070 10speed cassettes @ RM230
Weight of sram XG1080 10speed cassettes @ RM580 
Cassetter lock ring weight from XG1080 
The numbers of small components from PG1070 - see properly and count it!
now compare
view from both of the cassettes
Now if I were to compare with 9speed/ 10speed cassette (SRAM):
9 speed SRAM PG990 304g (RM230) - PG990 = X9
10 speed SRAM PG1070 358g (RM230) - PG1070 = X7
10 speed SRAM XG1080 237g (RM580)- PG1080 = X9/ XO?!?!
10 speed SRAM XG1099 (208g) 11-36 (RM990) - PG1099 = XX
I'm going to compare 9 speed with 10 speed cassette, the price vs. grade! for RM200 range,if you are using 9 speed you can get a SRAM PG990 X9 grade but if you are using 10 speed, RM200 you can only get x7 grade.
The weight never come into my mind as a consideration. 10speed cassette has an extra speed so the extra weight does make sense.
