Just wanted to know about the differences between the 505, and the 70. Are they comparable? Dose the 505 have the GB as the 70 not the 705. And if not how close are they? Was wanting to get a detector, but can't afford the 705, so was thinking about the new gold bug, but can't wait around. I say the 505 has like 50+ choices for GB would it work. Jess