Yes I think this is one of the bigger problems of these systems. So for example, let's say you've created a device that only accepts rice husk and your device pays itself off in 10 years. Now suddenly your neighboring country is subsidizing the gasification of rice husk. This means that the prices of rice husk increase and you're expected ROI is suddenly changed. This makes investing in these types of devices difficult and unattractive.

There are more agnostic systems, like fluidized bed gasifiers, but they generally create tar rich gas, which can gum up an internal combustion engine. That's why external combustion engines (Stirling or Steam) are so desirable as the pistons and internal moving parts don't come in contact with the flame front.