I came across a post on AskTom that seemed to contradict everything I've been told or read about tuning the buffer cache hit ratio and reducing Physical IO by aiming to get all queries satisfied by reading the blocks in the buffers.

The article quotes a paper by Cary Millsap of Hotsos, and is titled "Why a 99%+ Database Buffer Cache Hit Ratio is NOT OK".

Whats your view on LIP vs PIO and exactly what should we look for when tuning memory?