Some DIY friends put on a very interesting demonstration a couple of years ago at the Rocky Moutnain Audiofest. They hooked up two meters and played some music. One was an averaging meter and the other was a peak-reading meter. While the average meter was hovering around 5- 8 watts most of the time, the peak-reading meter was hitting 250 - 300 watts on transient peaks. So while 180 watts is more than plenty for most reasonable listening levels, you still may have transients pushing the amp into clipping. While these transients are extremely brief and the resulting clipping may not be all that noticeable, a higher powered amp will never clip, keeping things pristine.
Just some food for thought...
- Jim