I think Alfa Helicopters in Czech, went with the 135 at the time due to cooperation with Delta System Air (135 fleet) and the delay with the 429. They originally had an order for 4 427i's, which then became the 429. They now have 2 135's so I guess there is no reason to go to a new type.
The 427 has been quite sucessfull for them in the EMS role, and they were the first operator in the world to use it for this, if not the only, as far as I know?