Sorry I havn't heard the UM2 or W2, to my ears the w30 is brighter relative to the w40, but by no means a bright iem.
It is actually hard to tell if you would like the w30, to be honest, your brain gets used to the signature. It's only when you A/B another iem that you find there's this veil in the w4r's, sort of like tube amps with old records.
If by try you mean listening to them in a meet or buying from a place with a good returns/swap policy, they're definitely worth a try. If you mean buying blind, then you have to decide what you like in an iem, emotional vocals but not crystal clean, or a more true to performance experience.
EDIT: I just noticed you are in HK too, just go to shops in MK and give them a listen for yourself.