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As infiniti said, Ducky Shine keycaps are a but shiny to begin with
) They will shine up a bit more, especially the space bar, but not so it is blindingly obvious.
DSA is a different profile - all the keys are the same height. This is fine if you are using to using, say, a notebook keyboard, but a lot of people just can't get used to the DSA profile.
Also most PBT keycaps are thicker than ABS, and will block out a lot of the light from the LEDs. This is something else to bear in mind.
However Vortex have recently (?) released some backlight-friendly PBT keycaps with POM legends. I haven't read any reviews of them yet, but they definitely have potential to solve two problems at once.
http://geekhack.org/index.php?topic=61149.0