Disadvantages of using Bulb Turbine for Hydropower Generation

If choice of hydro turbine is focused on kaplan ( Vertical / Horizontal / S Type ) and Bulb Turbine , can any one tell the disadvantages of using Bulb Turbine ? Which are the normal and specific problems experienced if Bulb Turbine is installed ? There is not much advantage of efficiency if we use Bulb Turbine. However use of such Turbine in a country like India , serious operation and maintenance problems may nullify the marginal efficieny of Bulb Turbine.

Please share your experinece.