Having run both the 45 6001 and 45S here's some of my thoughts:
*This engine is lighter than the 45S and will address one issue I had with the 45S-that is that its mounting footprint is different than the 6001 (which is identical to the ST-46 making the interchangeable).
*Must be a really old/new case-my 6001 has a round venturi, not the earlier square one.
*Muffler mounting lugs-not there. 45S has them. Their absence makes for a light engine but will make it necessary to use a strap on muffler.
*Since it uses the 45S piston, liner and crankshaft I would expect a 45S run (fast, little break) over a 6001 (traditional ST-46 style 4/2/4). On the plus side it will be more powerful than the 6001 version.
*Like the 45S it will require a great deal of time to break in (not a fault, just an observation).
*Swirl venturi-not sold on them. They do work, maybe a little too good as the engine will really pick up RPM's when the plane reaches flying speed. The problem is that it makes it hard to set the NV correctly on the ground as the engine runs so much faster in the air. I went back to a traditional venturi on my 45S.
*Kudos to Enya for continuing to produce engines specifically for C/L.