I suspect it depends alot on your area and demand.
For example, here in Northern California, all the Cirrus instructors I know of are CSIPs and seem pretty busy. They get about $80/hr vs around $40-50 for a CFI from the local flight school (Cessna or Piper training) so I suspect it is worth it for them. Most only do Cirrus instruction.
If you are in an area with few planes and limited competition then being “Cirrus experianced” might get you the clients. Given the choice I prefer a CSIP as I know they must have some Cirrus knowledge. There are certainly great Cirrus CFIs and poor CSIPs, I guess. My insurance co. still refers to instructors as CSIPs, but that may be changing.
BTW, I believe there are criteria to maintain the CSIP rating too (certain number of transitions per yr etc.)