I too have a Ace 250 with all the coils and the Sunray probe. The probe will take some getting use too. I have had Sunrays on my Whites, Minelab,Fisher and Garrett, if Ralph makes a probe for it,its on my detectors. Once you use it you will love it. I have found with the probes when you find your target, pinpointing it before you dig you can use the probe to pinpoint the exact spot, on deeper ones you can push the pinpoint and go over the area with the probe and find that spot. When you have dug your hole and still having problems finding you target, move the probe away from the hole,hold the pinpoint down and bring the probe slowly to the hole and this will help find you target. Rememnber this is a one inch coil, so anything your detector will do it will do with the probe. I feel the YF-1 is more sensitve then anyonther of my Sunray probes. The most important thing to remember is look at the switch and make sure its in the right spot for what your doing. I have tryed to pinpont a target with it still on coil, I have also walked around thinking " not much here" then only to see its on the probe. You will do this at some point and you will look around to see if anyone is waching you switch it to what you are doing. The only problems is no one knows you moved the switch, you still will look around to see if anyone saw you do it.
Thank You
Tom Spencer