Very few modelers, even very experienced ones can set a safe needle valve on a 4stroke. Their rpm response to the needle is quite a bit less obvious. Beginners have a difficult enough time learning to set 2strokes by sound, and 2strokes have pretty obviously different sounds from rich to lean. The advice is often meant to save the newbies money replacing engines they've ruined. 4strokes are more complicated. Noone has to set the valves on 2strokes. And 4strokes with downdraft carbs can drive experienced modelers nuts when inverted. Upright or inverted, lots of them take a bit more attention to detail to either keep 'em from flooding or getting them primed. Pick one of those problems and there's a chance it'll be there depending on up/down draft and upright/inverted mounting. So there are more complications.

A year or so ago, one of our newbies to 4strokes showed up with one nobody at the field could get running worth spit. The list of things he was told you probably had to do was long. Need higher nitro fuel. Shouldn't mount some of them inverted. Have to use a 4stroke glowplug (very much more expensive). Shouldn't choke that specific 4stroke but only start with a mechanical starter. Shouldn't use a mechanical starter with that one inverted. Have to use larger diameter props to get flywheel effect for starting the smaller 4strokes...... and on and on. It was amazing to hear all the things the experienced 4strokers felt were normal for those engines. I doubt half were really true, but those guys thought they were. And it showed what 4stroke fanboys think is covered by, "just like 2strokes".

4strokes are kewl. But if you're thinking of putting one on your first plane, find an experienced 4stroker and talk to him from day one.... before you buy the engine would be day 3 or 4. And get him to explain how he sets his engines and be absolutely certain you fully understand all of it. And get a tach and learn to use it. It'll teach you what the sounds you'll need to learn sound like. Later you might not need it, but you won't learn the sounds cheaply otherwise unless you're very lucky and have a great ear.