Back just after I got Whm to cap (50 at the time) I put all attributes in Spell speed, got it to as high as could without forbidden melds and I didn't find it made enough of a difference to justify the build. I had a Piety build as well and while it was visible, it really didn't count as creative. Sure, I could cast maybe one more Holy before I was out of MP but it wasn't nearly as strong as the cleric stance and didn't really make me unique. Over time, I still find primary attribute (Wisdom for Whm) to be the place to put most of the stat buffs. Pug/ Monk is the only other one I messed with and it's the same there only Str being the asset.