Now that I've got myself a HUD I've noticed my winrate improve quite a bit. I've also noticed holes in my game which I needed to plug.
One of the best things about a HUD is knowing who you can profitably c-bet, and who you should never c-bet without a hand. Sometimes though I find the stats mean I can profitably value bet Ace high because my opponents will call down to the river and fold when they (frequently) miss their draws.
My overall stats for NL are 13/9 and for FL 22/10. I find the FL tables pretty juicy for suited connectors. small suited aces and small pairs as so many people see flops and you almost always win a large pot with a straight, set or flush. In NL it seems people play a lot more scared. These are people I put on the left of me so I can steal their blinds! 
hehe
So any thoughts on HUD and VPIP?