ive only found it harsh if the spice was burned rather than brought just the the vap point. Also if your smoking device doesnt cool the smoke, that can make it pretty harsh too and it it touches your lips can give you the sensation of numbing (but your lips have actually been burnt a little)

Ive not noticed much difference bnetween the yellow or the white. Infact the last time i tried the yelllow i must have got it just right, i hardly notifced the smoke at all and thought i never got any, went to take another hit then all of a suden everthing ewent like psycadelic tetris.

I prefer a small bong. the water cools the smoke down and seems to remove some of the taste aswell. but as soon as you burn it, tastes foul and makes thick horrid tasting saliva build up in your mouth.