Flame stratification on the cheapie venturi burners that those hex conversion kilns or even the commercial hex gas kilns tend to use are SO reliant on secondary air.
And yet those kilns have little to no chimney height to actually create the draw needed to provide that secondary air. Power burners are perfect for kilns with no chimney! For the price of the 2 to 4 venturi burners they typically use on the little round kilns, they could build a single power burner with the same or greater output. The real cost of burner systems is in the safety equipment- solenoids, flame sensors, etc.- not the burner itself.
The other great thing about power burners is that you can drastically change the orifice size without messing up the burner. So if you don't have enough power, you can fix it by increasing the orifice size (as long as you have enough gas volume coming in, of course). And if you find you need more air, you can put on a larger blower.
I think that many of the folks who convert the round electrics into gas think that because the round raku gas kilns work well, it should also work for a cone 10 reduction kiln. But the truth is that any crappy burner setup can get a raku kiln to temperature. 1850F degrees is easy. But as you get into higher temperatures the lack of insulation in those kilns becomes a real issue, as does the uneven temperature and atmosphere.