I can't speak with any experience concerning conversion varnish as I have never used it but I will readily argue that pre-catalyzed lacquer IS NOT a more durable finish coat than polyurethane. My intuition leads me to believe the same about varnish.
Pre-catalyzed lacquer is a great benefit to the woodworking community in that it causes the lacquer to achieve it's full cure characteristics much sooner than standard lacquer. However, it is only achieving them quicker, they are not being improved or increased.
Gee whiz Ed, holy macrimony, calm down, you don't have to shout. I will agree with your take on lacquer. But first we must look at exactly what we're talking about. I've tried just about every type of finish, both spray, wipe on, brush on, and I can only speak from my own experience.
For a simple explanation of lacquer, the pre-catalyzed is considered catalyzed at the factory, so the can you buy doesn't have to have any catalyst added. Catalyzed, or post-catalyzed is the lacquer that needs the catalyst to be added. Basically the major differences lie in the use time and shelf life.
So, now that we have distinguished the terminology, many on the forum get those two mixed up. The durability factor of a finish depends on many factors. Of the choices, not in any particular order:
Lacquer (both pre-cat & post-cat)
Oil base polyurethane
Water based polyurethane
I may have left out something, so I apologize. Each has its own properties and whichever one is selected, should be tested or used with compatible surface preparations, such as stains, dyes, tints, fillers, and sealers. Testing for durability will not give a standard answer because the applications may differ in many ways as to use. But generally speaking the order of durability for conversion varnish is higher than lacquer. On a general scale of use, oil base polyurethane exceeds conversion varnish. For some uses, waterbased polyurethane ranks as high as oil base polyurethane for some uses.
Lacquer isn't a preference for floor finishes, whereas for a long time oil base polyurethane was the choice. Nitrocellulose lacquer is an easy durable finish in a lot of circumstances. Polyester lacquer exceeds the realm of either nitrocellulose or acrylic lacquer for hardness and durability. The advances in crosslinked waterbased polyurethane has produced an extremely durable finish. It is becoming a very popular finish for flooring and furniture. Shellac, although one of the oldest used of finishes provides a good surface, is easy to use, but not as durable as oil based polyurethane.
Considerations for the choice of finish may include the steps in application, ease of use, dry time, touch up/restore capabilities, type of chemical resistance, shelf life, and compatibility to whatever may be undercoated.
Other factors on choosing a finish may include the extended life of the build of the finish and how well it will fare in its thickness. There are other factors in choosing a finish for durability, as the furniture/wood industry has its priorities for finishes, and uses electrostatic processes, whereas, the woodworking shop/cabinet shop/ DIY'er/hobbyist will have changing demands for use. Fortunately we have many choices, and that's what makes the world go 'round.