I wouldn't say cheap is one of the pros...There are other engines that cost the same, maybe less, that are much better engines. The Thunder Tiger GP .42 is an example.

The O.S. .40 LA is generally a very reliable engine after break-in. There seems to be more trouble with them compared to other O.S. engines, but they are still good engines. They are quiet and reliable. That's as far as the pro's go...

The cons are that it's unusually weak for it's displacement. The Avistar and Superstar are good matches for it, but it's still underpowered in my opinion.

It's got plastic parts which are easy to break with more screws to come loose and more places for leaks to start. The ones I have messed with seem to run very hot in the summer and if you run them rich enough to cool them off, you can barely get off the ground. They just can't do the job on a .40 size airplane as far as I am concerned.

The Avistar and Superstar Select is an otherwise good setup to start with...You might want to take a look at the RTF Tower Hobbies trainer which comes with a GMS .47. The Hangar 9 Alpha is another decent setup with a decent engine.

I've always recommended a good ball bearing .46 for a .40 size trainer. My favorite is the Thunder Tiger Pro .46...