Todd,
Sorry for the name confusion.
Based on the most recent tests done, I suggest never using a tag on deleted. It may improve some selects against small tables, but those will be acceptably fast without the tag. The problem comes in when the tables get large, with large tables a tag on deleted may result in a fully optimized query that runs slower than a partially optimized one would.
There was an article in a recent issue of FoxPro Advisor that discussed this situation in great deatail.