The problem you have and are ignoring is the greater speed puts you more at risk on a faster bigger bike.
I ride my Click 160 on Sukhumvit and it's fast enough and i don't need additional speed, not once have i needed it, same on my previous Click 125.
I've had big bikes in the UK as it was the norm, they're over rated, i had a 500, 600 and 800 BMW, much prefer the smaller scooters