Welcome to the forum :hello2:
You have received sound advice from a conspicous consumption perspective! So I really have to play devils advocate.
Here are some of the problems with the older non FI Sveltes (400s')
1. Carb icing in cold wet conditions (Brit winters) - you don't have those so no problem there then!.
2. Rear wheel seizing onto hub spline. Well documented problem and can be entirely avoided by regular mantenance and application of anti-seize compound.
3. Rear spline insert failure - most have these design/manufacture problems have presented by now and you would be most UNLUCKY to experience this.
4. Rusting exhaust systems - this is certainly true in Northern Europe where salt is laid down on the highway in winter - do you have winters like that in Singapore? Anyway aftermarket systems are available that are cheaper and more durable.
At the end of the day - if you save $4000 you could buy a new rear hub/wheel and a spare exhaust and still have have $2500 change - not that you would have to do that! BTW the trunk is smaller on the Olde Svelte but you CAN get a full face helmet in there OK.
In Sum, my contrary advice is to save the money and get a well looked after $2000 Svelte at least when/if you decide you want a 650 (Lardy) you will have $4000 + what you can sell the Svelte for towards that purchase. If you go for the new Svelte you will use your capital and take a slam on depreciation.
In addition the new 400 FI is not foolproof and one member here has had catastrophic engine failure!!