Note that the OP is in Singapore. What's the climate there and what batteries are available?
My new 2014 Pat with 2.4 l engine comes with a 525 CCA battery. I'm not sure of the group size, but it looks pretty small. Interstate lists it as a group 86, but I have also seen group 25,26, and 35 as fitting (confirm yourself).
Bigger CCA is not always better. With case size remaining the same, a 700 CCA plus battery will have more, but thinner and more tightly spaced plates compared to a smaller CCA battery. The thinner, more tightly packed plates MIGHT have less longevity, especially in hotter climates.
You don't need the higher CCA's in warm climates. So, it's a trade off.
The worst enemies of car batteries are heat and repeated draw down of the battery (lights left on, etc.), which kills them quickly.
I wonder if the location of the Pat's battery contributes to higher heat?
My opinion would be not to go more than one CCA size up (640CCA +/-) because of the plate info given above.
Also, regarding Optima batteries. Since Johnson Controls took over manufacturing of this battery, the internet buzz is that quality has suffered greatly. Just a statement not based on experience. Check it out yourself.