Main reason they didn't stay around was lower MAUW of 3000lbs about 50lbs of which was taken up by the water-meth injection system! This dropped the TOT by about 50deg when you were pulling all its available power.
My first ever 206 trip was a jolly in an A in Oman (ISA +25) and the pilots who flew them deserved respect!
You still see a few converted ones in UK. BLZN being one, with which we did some good work in Ethiopia at altitudes of 10,000ft+