One of the "features" of my Casio PX-350 was its keytops:
The Simulated ebony and ivory keys offers the luxurious feel and texture as well as the smooth touch of a grand piano keyboard. The minutely detailed crimp surface finish inhibits finger slippage due to sweat and gives the sensation of a perfect fingertip fit, even when playing for extended periods.
The keytops are fairly heavily textured -- they look and feel like heavily-worn ivory, with the grain of the bone evident -- and they were noticed in several reviews. I grew up with an acoustic piano with shiny keytops, which I just accepted as the way things were. So they were a departure, for me.
I noticed them for a few minutes, and then just enjoyed playing the instrument. I didn't notice any more sweat, or any less sweat, and my style didn't involve much sliding across keys. So _for me_, they were (are are) no big deal.
I'm tempted to say to the OP:
Get whatever DP feels best. If it has shiny keytops, and they bother you, get some fine sandpaper or steel wool, and turn them into matte keytops.
But that might get plastic dust into the action, and would certainly complicate getting warranty repairs. (Steel-wool scratches might also be quite different from a molded-in pattern.)
It's not something that _I_ would get hung-up about. But (as we know!) people differ.
PS -- FWIW -- When I played a P-515 for a few minutes, my immediate reaction was:
. . . "Oh -- this is really nice! Much closer to an acoustic piano,
. . . than a P-125."