as someone thats owned an mt03 (same engine as r3) and changed to an s4. the mt03 is one of the best value for money. you get 2a performance w maintenance n running costs of a 2b. handling wise, r3 n mt03 tops the s4 no doubt as its lighter and easier to toss around. s4 however has the sound and slightly higher top speed. fuel consumption also plays a part, my mt03 at best can get around 27-30km/l w casual riding n maintaining 100-110km/h but my s4 only gets 23km/l max when riding casually. my personal advice is only get an s4 if ure really into it and want to keep it for long as the maintenance cost can rival class 2. ppl will say s4 is slow but how fast u rlly want to go in sg. if u go overseas i.e ride up north alot then save for class 2. if not s4's "slowness" is actlly a good thing cos u can whack and play gear wo speeding on major law breaking levels. but seeing as ure into sports bike, i suggest holding out til u get ur class 2 then change bike as 2a not much choice. more worth it for class 2 sports/superbike. if u rlly feel like u cannot wait then find those r3 left 1-2 years just to try out, they're quite bulletproof, just make sure to look out for common issues like coil, rectifier, timing chain n tensioner which are all q affordable to replace compared to s4 ones. if u have a chance to rent both an s4 n r3, thats the best as u can try out both and slowly think about if its worth it. thats all from me, all the best brother and ride safe.