Good overall, but I wanted to make the climb to Warrant Officer roughly equivalent to the climb to Captain. Beyond the former is commission; beyond the latter is flag rank. The chief problem we have (pun intentional :D) is that we only have a single example of an important enlisted character: Miles O'Brien.
I am minded of my brother's six years in the Navy. He served aboard the USS Sam Rayburn (SSBN/MTS-635) as a Machinist's Mate after completing Nuke School and was I believe a Chief Petty Officer at the time he mustered out. Elite training groups seem to advance in rating faster than their counterparts.
*shrug*