You've brought up an interesting question - in general terms - what are the relative advantages of having a separate transmission? I suppose there could be major differences in the new unit engine compared with unit ones in older machines like BSA, but logically, they seem similar. Given that, has anyone had experience with a unit type engine who could give some insight into relative merits of each. I can think of some. If something happened to the trany part or to the combustion part (piston and rings), the other might be damaged through loose parts being thrown about. Repair of the tranny would seem to be easier with the older type, just unbolt, take to the bench and work on it. And then the idea expressed above of a washing machine effect. But the unit one may have fewer parts or be somehow simpler or more efficient. Anyone have thoughts or experience to add?