https://www.mtbr.com/spotlight/srammediacamp06/sram.shtml
New SRAM X-9 Rear Derailleur The new X-9 utilizes the same technology as last year's X-0 shifter and derailleur. Materials are also up to last year's high X-0 standards, meaning weight is down and shift performance is better.
Available in three cage lengths Long, Medium and Short
New polished look.
1:1 actuation ratio and Direct Route Technology means lighter effort shifts.
Weight: 230 / 227 / 212 grams for rear derailleur depending on cage length
160 grams front derailleur
MSRP: X-9 rear derailleur: $99
X-9 front derailleur: $48
Shifters: $29 to $128 depending on model
I imagine that if they are pretty much making the X.9 to the standards of the X.0.. that the X.0 will be better now to justify the price difference...