Who has used Legend for there horses and does it truly help? Who's ran ones with bone chips 

Legend is a great product but it takes a couple days to work and only stays in the horse's system for about 4 days. It won't take the place of injections but is great as added support for a something like 3 runs in a weekend.

Horses can and have been run with chips, but it's highly dependent where  they are. Sometimes chips floating around or on the articular surface can cause a lot of cartilage damage and make things worse. Sometimes, depending on location of the chip, doing surgery can cause more damage retrieving the chip vs. leaving it in. It's a case by case situation. 

My gelding has a chip in his ankle.  I bought him as a 8 yo.  Vet says it looks like it's been there a long time and doesn't bother him.  He's a 1D/2D consistent horse. Never taken a lame step in that foot.