I wrapped my U/D pipes as much as I could. If I could have got ceramic coated pieces, it would have benn better, but I had to go with the wrap.

The only bad things I've heard about wrapping is 1) it accelerates rust, because water gets trapped in there/the wrap stays wet longer than the pipes would normally, and 2) it can act as a wick if you get a flammable liquid soaked into it and it somehow catches fire.

Plus, it is really itchy if it touches your sking when wrapping it.