Why is the gracie gift taught anyways? I just can't understand why someone would teach a technique that leaves you so open.
I used to use the lockdown alot when i first read about it. I have used it to tap people, but i dont live by it. If you really want to develope a half guard game then you should work the basics from that position over and over. When you get good at regular half guard technique; then try to go for newer techniques.
Also you should ask your instructor about this too.