Rattles are usually down to unbalanced wheels or similar. They shouldnt rattle at any speed! Listening to the engine isnt number one technique at all. If you've never fitted a rev counter, you dont know what the limits are! You could be shifting well below or above redline.
Also, looking at a rev counter isnt a destraction imo. Its not like your staring at it through the gears, you only glance when you think you need to shift. No worse than looking at the speedo!
