I have been commuting on a bike in HK since 2008 and my gear only changed once since then. At first I bought a BMW Venting Machine jacket and a Force Field integrated chest/back protector (looks like a bullet proof vest); pants wise I went with just heavy weight denim jeans somtimes with full race boots or hiking/work boots. The zipper finally broke after 5 years of washes and now I am wearing a full Rev'it Tornado suit all the time and just change in the office or bear with the "looks" when I'm walking around. I choose the Tornado because it has a waterproof and thermal linining that I can put back in the winter. In the winter time textile jackets can be freezing cold for the 2 weeks or so winter we get here.
I figure with the low speed crashes in HK you may not need all the abrasion resistance protection offered by leather. Impact protection is more important IMO, hence the chest/back protector. You're more likely to bust a rib or have internal injuries in the types of crashes in HK without extra impact armor; most suits even leather does not provide chest protection.
It is UNbearable to wear leather in HK unless you have a large pannier set to carry the 50 bottles of ice cold gatorade to cool down every 30 mins. They are nice during the fall and winter; if you have the $$$ to splurge buy both the leather and textile.
Of all the things I felt kept me safe over the 5 years of riding in HK (24,000kms on a VFR, 10,000kms on a Vstrom and 13,000kms so far on a ZZR1400), I think it was the bike. Drivers tend to look down on smaller bikes and scooters. Other than the ZZR I have had HUGE panniers with 3M reflective tapes and a Stebel Nautilus air horn. The Vstrom was the best where I installed 80watt LED flood lights as day time running lights (they will literally blind people at night). And with after market pipes, they cannot say they did not hear you. So while people say a beginner should start with a small bike, I think there is a certain safety factor from being noticed and respected by cars in HK with a bigger/louder/meaner looking bike. When my current helmet goes out of commission in a few years I want a custom painted one with a mean looking skull to scare the drivers LOL
Along those lines, wearing proper gear and shiny metal plated gloves will also get drivers' attention/respect IMO.
That or get yourself a BMW R1200RT, a white helmet and a flourresent yellow mesh jacket; that ought to get you attention on the road LOL
Lastly going back to the topic of leathers in summer, remember that rider fatigue is a problem if you are over heating. In the last few weeks even in my textile suit I felt like a heat stroke was coming on after making the mistake of not drinking 2 pitchers of water before heading out on a ride. So if you're in black race leather stuck in traffic you will definitely get heat stroke in this weather which is more dangerous than if you "go local"