Use the textured side for pasting with CrOx. Leave the smooth leather for normal stropping.
If you decide you want to try another kind of paste, I think you should get another maybe cheaper (as in less nice) paddle for that rather than treat the smooth side of the one you already have.
You need a plain leather surface for stropping, so unless you have another strop for that purpose you shouldn't paste both sides of the SRD paddle.
James.