Uhm, kinda surprising but ok. Guess its just me, disregard my post then, tho i wanted to show you, how players (probably just a few but still), change wall texture to improve, at least for them, its looks. They use totally diferent texture to the default one. So just take it as an example to get an idea.
EDIT:For me, the grass on carpathian is too dark(too green) in combination with the wall texture there is. Maybe you could try making the grass "less perfect", as it is now, there no yellow grass straws, just perfectly green grass. I dont think this is the way paintball grass would look, because of all the action going there (i could be wrong tho, never been to paintball field).
AGAIN, this could be just me, so lets wait for others to see what they think. I rly like the wall texture on caprathian, tho i dont like the combination of this grass + wall texture.
EDIT2:
I have been going through some maps and found more textures i dont like...
grass1_4 - it looks fine outside the game, but ingame it just doesnt look real to me, maybe adding more of yellow instead of white would help?
rockp2_7 - sass texture, this one just doesnt look 3d or anything to me, i cant really feel the rock in this texture (weird sentence ^^)
About the nonHD textures, i couldnt find where they are used, at least these of which you didnt have low-res version. But, i found other textures which arent HD and are used on maps:
metal4_6 - nhb, used on lights (if its HD then i guess its just stretched weird)
grass1_8 - pbcup_renoir - dirt under water/in sideway
woodp1 - duck, midhigh house wooden "sides"
Going back to rock5_2, another problem i found with this texture is that it doesnt look HD if its next to another HD texture: