Most flyers trying the LA 40 seem to overprop it. It does require a smaller prop than the 46, around 11/4 or less, or the new 3 blade Master Airscrew 10/5, maybe trimmed a bit. The 40 looks like it has a bit higher stock compression than the 46. It usually requires adding gaskets or enlarging the head bubble, where the 46 often will run OK without those changes.
When a maker bores out a case to fit a larger sleeve the ports on the larger bore usually end up being relatively smaller than on the smaller engine. Makes the engine run more in the classic stunt style like the 46. For max power the ports always end up taking up virtually the entire circumference of the sleeve. The 40's ports are relatively a bit larger than the 46, making it tend to be a bit peakier, slightly higher rpm engine.