first of all im getting over a cold/flu thing and i didnt smoke as much as i really wanted too...i didnt because id rather just save my strength for next weekend when i can have some quality time with the phx.

to answer your question though ive always thought of it like this.

with cold water yeah its cool...cold water..ice cubes..the works. and its a cold hit and all but ice makes me drool more haha and plus its fucking cold when your out in the garage.

with hot water though if you think of it...the "bad stuff" gets filtered in the hot water better because the bad stuff is closer in temp to the water.
toxins/carninogens are hot because of the smoke/fire to burn them so if the water is hot too...the transaction through the smoke is smoother.

bottom line is this. get your bong. smoke a bowl with cold water and ice. then smoke a bowl with really hot water. judge the difference for yourself.