G'day SkiWhiz.
I own both machines and find their performance to be mostly on a par with each other. Just a slieght correction Digger, they both have 12 notches, wich operate in about the same spots.
About the only thing that the X-terra has over the Ace, is a volume control.
As you found with the Ace, once you learn how to pinpoint with it, I think that it is a bit more accuate than the X-terra's. It's kind of like comparing a manual verses an automatic transmission on a car. The pinpointing on the machines is one of four main points that seperate them. The X-terra's will give you target information through the volume and pitch of the pinpoint. A smaller target will be quieter and a screw cap if shallow, will screem at you. On the Ace,you have 2 main pinpointing methods, you can detune for both farther accuracy and target information and you still have constant depth read outs which can also help in determining if a target is junk. Also with the Ace, you can pick up target information by listening to how the target falls off the pinpoint. But again, this also only applies to targets in the top 2 inches.
Two things that the Ace has over the X-Terra's is 1) The Ace is an absolute killer at hunting in close to metal objects. By dropping the sensativity to 1 or 2 bars, even with the large coil on, you can still pick up coins that are only 2 inches away from a pole! The sniper coil is a coaxial coil, which means, that when you press the pinpoint button, you only have a signal that will go down and NOT up. I have found coins this way while the top of the coil is in DIRECT contact with the metal above it! The X-Terra's can't compete with the Ace for this sort of hunting. 2) The Ace is a much better balance machine. The X-Terra's are far too long. I hunt with mine 3 holes shorter than it came with.
As far as the audio and meter go, I prefer the X-Terra's. After using the X-Terra, then going over too the Ace, I found that the sounds of the Ace felt abrupt, and the TID a bit harder to see. I much prefer the number system of the X-Terra.
One last thing. The X-Terra has a quicker recovery than the Ace, which is helpful in busy ground, but the Ace with it's standard coil, can cover more ground than the X-Terra.
If you still own the Ace, then you aren't going to gain anything by going to the X-Terra 30. Personally, I think that they should be the same price, as the quality and general performance is about the same.
What ever you choose, you will enjoy either machine.
Good luck.
Mick Evans.