loaded question??
Depends upon where you are
We own a 141 Helicopter school in the US (British owned) and in my humble opinion Turbine time is virtually worthless here if you have less than 1,000 hrs.
You would be expected to teach until the 1,000 hr PIC point in pistons regardless.
Insurance companies in the USA will not (perhaps they will if you throw enough cash at them) insure pilots for turbine machines if you do not have at least 1,000 hrs and in most cases an IR. Its the liability risk they are very concerned about.
What most CFI's do at the 1,000 hr point is go into one of the following operations in the Gulf (Airlog,PHI,ERA, Rotorcraft Leasing) or Temsco in Alaska to get their first turbine job. These companies all pay for the piston - turbine transition. Therefore in the US I wouldnt bother, let your first turbine employer fund your transition.
I'm not that well versed with the European situation but I am led to believe that insurers are not quite so hung up on TT (I know private owners flying turbines with 200 hrs in the UK, mainly Bell 206's and Gazelles) and thus will insure lower hours pilots to fly turbine machines In this instance I do believe turbine time would be an asset to an employer (the more aircraft you are qualified to fly he more flexibility you have).
It really depends upon what your career and location objective is.
does that help? - probably not!!!!
Geoff