FYI Taser has advised that the XREP may soon be phased out. Last time I checked the cartridges run approx. $135 each, and must be purchased in packs of 5 (LEO). Practice rounds are expensive but nearly as much as the live rounds. (I think they were advertised as about $90 per pack of 5; packs of 50 were what we used at the course). I volunteered to be hit with the XREP at an instructor's recert a few years back but they refused.
With regards to the live projectile, the barbs on the front usually require ER removal (few live deployments compared to the handheld Taser and other LL weapons), and the 'cholla' rear needles are also long and thin enough to do the same. Amazing design that actually packages miniaturized Taser components in a 12ga cartridge. A proposed link to Taser's wireless AXON camera (sounded totally "Buck Rogers" to me) would allow the firer to reactivate the deployed XREP projo remotely from over 50ft away; not sure if this was ever fielded.
Compared to other 12ga LL rounds (CTS SuperSock et al) the XREP does not deliver equivalent LL blunt impact, and is much more likely to cause cuts/wounds.
I have pics of an early yellow-fin version I'll try to find. There is an identical pic of the cartridge and deployed projo (live and practice) at gtdist.com in their Less Lethal product section.