G'day trueblue.
I read your post a couple of days back, but before I could respond, the Norton blocked the site and I'm only now able to respond. It looks like you have had some good responses already. I haven't read them all, so I'll respond with Aussie coins in mind.
We seem to have swung similar detectors. I started out with a Tracker 4, and have owned an X-Terra30 since they've been out. I have also owned the Ace for just on 2 years now. I haven't owned a Tesoro though.
The X-Terra 30 and the Ace are very similar detectors in a sense. Both have 12 notches eta. That said, they are also very different machines too. After using the X-Terra, it took some time to readjust to using the Ace. Mainly due to it's tones. They are not modulated, and at first, it sounded like a blunt instrument. Once you train your ear to it though, you get to figure out the good hits.
One of the really good bits that you will like about the Ace, is that it is a fairly reasonable detector at sorting out whether you have a screw cap under your coil, or a gold coin. It will take a bit of time to learn, but this happens in pinpoint. Coins will have a sharper signal fade than a screw cap. Unlike the X-Terra 30, where a $2 coin can bounce down to 28, the Ace will always lock both gold coins into notch 8 (equivalent to 32 on the 30). This is also where the Bell tone kicks in. Very handy. I've only ever had 2 gold coins come in at a lower notch.
As far as pinpointing goes, although the method in the manual works, it's not the best way to do it. It's probably why some folks have bagged it out as a poor pinpointer. To date, I've found it to be the most accurate. the best way to do it, is off the 12 o'clock position of the inner coil. If you listen closely to the audio drop off while doing this, you be figuring out what you target is in no time. If a target is 2 inches or closer, then all targets drop off suddenly and you won't be able to sort them out. They will however be very easy to locate due to the accuracy of the pinpoint (at this range). If you lift the coil a bit, it seems to soften the edges of the signal enough for you to be able to figure out your targets. BTW, a deep large target will keep hanging onto the pinpoint, which makes them easy to figure out. There are clues for some of our other coins as well, but I won't go into those now.
Something else the Ace does better than most, is hunting around play equipment. The standard coil is pretty good. Dropping the sensitivity down to 3 bars, will get you in as close as 3 inches. If you get the sniper coil, if you don't mind forgoing discrimination, you can get to within an inch of an upright, and directly under metal. I have pinged coins with the top of the coil in direct contact of the metal above. You can only do this in pinpoint though. The coil is a coaxial (double shielded) and when in pinpoint, it gives off no signal to to side of the coil, or above it, hence it's abilities.
I'm waffling. If there is anything that I can help you with, then fire away.
Mick Evans.