just talked to SCB. they admitted that they changed the rule some time in 2008 (both about HKD 15 = 1 mile for <=10k miles, and about fee having no cap, used to be HKD 300 cap).
they said they have sent out notice on this but frankly I'm someone who read every fine prints of everything sent to me by banks / credit cards / airlines / hotels / etc and I never read anything - so I suspected they probably just changed the rules by themselves secretly without sending anything (like what Asia Miles did lately), or that I didn't have any transactions that month and so didn't get the statement and hence the notice that came with it.
and the funny thing is that the rep just now on the phone asked me to go on to the web and said I should be able to find it there as I can do the redemption online - finally what he succeeded in showing me was that the item was listed as 1000 Asia Miles, with bonus points required = 12000 and redemption price = HKD 0.0 - failed to tell and convince me where I was supposed to see the fee at all except this HKD 0.0. these fees were just buried somewhere that even the rep couldn't find.
anyway...I need to re-evaluate a bit then given this 10k miles = HKD 100 fee, whether this SCB Visa Infinite is still the best deal for me (probably should use DBS Amex a bit more then whenever Amex accepted). need to do a bit more math.
BTW SCB Amex seems to give 6x for spendings at a lot of travel agents too, including the two who's our corporate travel agents. will see if I can start getting 6x for all my plane tickets - if so, a really excellent deal...