Just read this whole thread
I just came across this thread and it seems to have fizzled out. This has been an informative read and I am sure others will come across this later too, so I just want to throw in my 2 cents.
As a local HKer and aspiring cadet, I have to agree with betpump5 and 404 Titan. Housing allowance WILL make a huge difference. 40k a month in Hong Kong is really not that bad, especially considering end of year bonuses normally take care of taxes. BUT, the cost of living here is a bit weird in that the fixed portion of cost of living (mainly rent) is by far larger than the marginal portion (food, entertainment). I say this with experience living and studying in Canada, the States and the UK. In those places, living it up as a student can exceed your rent. In Hong Kong, the reverse is definitely true. So why is housing allowance a big deal? Because, the marginal value to your standard of living from 20k can mean the difference between not starving and living very comfortably. To put this into perspective, a live in maid's salary is 3k, i.e. you can hire about 7 maids with your housing allowance. At the same time, 20k is what it costs to rent a decent pad in downtown Kowloon. Basically, housing allowance IS going to matter.
Some people have said it won't bother them that people of lower seniority will get paid more. It may not now, but it will when you get here. Hong Kong is an extremely competitive society. Status is everywhere, but no one talks about it. For example, Hong Kong ranks number 1 in wealth gap. Google 'Hong Kong cage home' if you want to know more. Comparing yourself to others will become second nature within a year or two of moving here.
As a local HKer, I would urge any international looking into the CPP to live in Hong Kong for a few months, or at least visit before deciding whether the CPP is 'worth it'. Hong Kong may seem really 'western', and parts of it is, but the culture and economics of Hong Kong is also very different from Europe, America or wherever you're from.