I have very little experience with wood pellets so please don't hold me to my answer .
There is a ratio or relationship that should maintained in the gasifier of fuel surface area and reaction area, size or volume .
With the HUGE surface area of wood pellets the reaction size and volume ( diameter of choke and distance from choke to nozzles ) would need to be very small.
If you use wood chips or pellets in a gasifier designed for wood blocks it will run cold and make tar and in my case bent push rods . ( 460 ford 3/4 ton 12 years ago )
Also as you have stated the disintegration of the pellets.