Here I am, in a bit of a quandary. I have both an Ace 250 and a GTA 1000 PM.. which one to keep? They seem to be about equal in small target sensitivity and depth; the Ace is lighter with only 4 AA's while the GTA has many more features and better notching. As an aside, can the recent spider/elliptical concentric be used on the older detectors (maybe by swapping connectors)? Whadya think? ...Willy.