OK well let me look on the other side for the 4s. I have a saito 82 and do like it, however they vibrate/shake more, weigh more for similar power in many cases, and often require more nitro for power or better idle. While my 2s will run fine on 5% the saito needs 15% nitro to run smoother. Obviously they cost more too, and crash damage is more likely. ($$) Anyone dispute this? The positives are above.

A 2s often needs rpm to make a lot of power therefore they don't sound as nice. However they are light, very simple, durable, cost less and are easier to tune. Probably the best thing you can do is to buy a quality 2s engine, the better carb often making much of the difference between it and a cheaper engine.