Is an EGR valve like eating poop?

[knorsk]

ahhhh...the EGR valve. This puts inert gases back into your engine to keep it from combusting at high temps and lowers the knocks and pings. It keeps out the harmful Nitrous Oxides. It usually is only working while at idle and low cruising speeds. Wide open throttle and the EGR doesn't kick on. Does it send harmful deposites back into the engine? Or because of its function does it prevent more harm than it causes? Or is it just some low emmission device?

Anyways, some people disconnect this device. Does anyone know if there are any gains to this? Is it better or worse on the engine to have the dirty air spit back into the intake?

I'd really like to hear a mechanics input on the subject. To me it seems like a 50-50. Your engine doesn't combust at much at idle because of the inert gases, but at the the same time the inert gases come along with a lot of dark unburnt grime. Just something I'd bring up because it seemed to be popular.