Hmm I may be wrong.. I'm researching up on filters at the moment too. I saw on Hoya's website that they have CPL filters with different coatings... Pro1D(with DMC), Standard, HMC, Ultra and S-HMC.
http://www.hoyafilter.com/products/hoya/gf-04.html
http://www.hoyafilter.com/products/hoya/pro1d-04.html
Not sure if the shops in SG carry all of them though.
Does anyone knows is S-HMC coating better or Pro1D with DMC coating? I'm confused.