VedaDalsette, I think you'll find that the Adaptive Sampling made most of the difference there. It does the same on my MacBook Pro too, setting it to 0.002 for me reduces the render time by over 30%. Obviously higher values mean more noise and lower quality - but I find it a good tool to use for quick renders before final.

I started this thread as I wanted to see what people thought were acceptable render times so your comment about getting impatient certainly adds the that body of results, thanks. 

Personally I've always left my computers rendering while I sleep so final render times don't tend to bother me too much - but obviously faster preview render times while working are better.

I chose this scene for this thread as it was moderately complex with high default render settings, was free and would provide a good compare across a variety of machine specs. It's been real interesting so thanks to everyone who took the time :)