Our firm has extensive experience analyzing evidence and data related to TASER incidents (see our article). We strive to stay up to date with emerging technology and Leroy and Tom with Seattle PD were kind enough to allow us to test fire the new TASER 7 that they are testing and evaluating.
There are significant differences from other Axon-TASER models, including new cartridges and probes. 
The T7 cartridges are available in 3.5 and 12 degree configurations to provide user options for range/probe spread.
T7 Cutaway cartridge
impacts of T7 probes
The probes now contain the wire which unspools as they travel down range. The probe head will detach at tangential impacts. Forensically, the probes can analyzed where the wire is crimped to the probe head!
X2 probe vs. T7 probe (bottom)