OK,
you are right. Four strokes will never work inverted becasue of that stupid, poorly engineered intake pipe.
Too bad I just maidened yet another P 51 today with a magnum 70 FOUR STROKE mounted INVERTED, and had not one problem at all. of course, I did have some problems at first until I got it all worked out by TUNING the engine PROPERLY. THe engine had previously been mounted 90 degrees on a cub. Mounting it inverted, on a different plane with a different fuel delivery setup created the need to actually TUNE the engine. Once this was done (about a two to three minute job) it never died--during four flights today. Simply Amazing.
Of course, I followed that by flying my Top Flight Gold Texan that I built and currently fly with an evolution 100 two stroke--also mounted inverted-and it too flew like a champ. Of course, I utilize a header tank on it to properly align the fuel storage with the carb. Never had one ounce of problems out of it either (please, let's don't start an argument about using header tanks to adjust fuel delivery aspects on this thread).
It's amazing what can happen when your plane is set up PROPERLY--two or four stroke, it really doesn't matter.
But, you are correct. Whatever works for you is what you should stick with.
Send me all of your worthless four strokes, please.