I use one of these at work:
http://www.ridgid.com/Tools/122XL-Copper-Cutting-and-Prep-Machine/index.htm
Now regarding noise. I'd have to say that the piping would have to be rather undersized for noise to be an issue. Undersized piping will create excessive velocity, but you would most likely hear that as water hammer.
The most common issues for noise are valves with washers, most notably stops, where the rubber has come loose from the stem. This generally causes a whistle, moan or chatter. Worn out ballcocks are also notorious for this.
A severely restricted/corroded fitting can cause noise, as can a damaged globe or gate valve.
As far as the piping itself causing, doubtful.
Now, on to why one needs to ream and deburr their cuts.
The duller the cutter wheel (and the less patient the plumber is) can cause some big time issues with erosion. Recirculated piping systems are where you'll see this.
Combine a pipe not properly reamed and an oversized circ pump (creating excessive velocity) running 24/7 and you'll see pinhole leaks downstream of the fittings. I've seen this on a few occasions in facilities less than five years old. The unreamed pipe ends create/cause an eddy as water flows past them. These eddies bounce off the interior of the piping as they travel along, eroding it away little by little.
In a box somewhere around here I have an 8" long piece of 3/4" L copper with a coupling in the middle. It was a piece that developed a pinhole leak on a recirc line. Looking from the upstream end, the pipe is nice and smooth. Downstream of the coupling, the interior of the pipe resembles the Grand Canyon.
During that repair, I cut an additional 1' off the downstream line because of erosion. That pipe had been in use for 3 years.
I ream every piece of pipe I cut, and so does anyone who works on my jobs. Be it copper, plastic, steel or cast (cut on the chop saw), dwv water gas or process, they all get the treatment. Even the vent piping gets it.
Lately, we've been using alot of water soluble flux. Water soluble flux contains no petroleum, so it's not a good lubricant when assembling fittings. We've had to be pretty deliberate with deburring to ease assembly of the fittings. I really have to resist the urge to reach for the Nokorode several times a day, lol.