Listen to Sandman. Here is a post I just made in another topic.
I have an Ace 250. Compared to the Tesoro Silver uMax I just bought, the Ace is a toy while the Silver is a tool. The Silver uMax is 10x the detector either the Ace or the F2 is. I don't have an F2 but it is getting pretty poor reviews from folks on here that I trust.
With the Silver, it 'sings' to you when you should dig. Plus, I don't like having to walk around looking at a screen. With the Silver, you just listen until it tells you to dig.
If you're coin hunting and turn the discrimination up, there is no doubt when you hit a coin. I found 3 pennies about 2" apart the other day, and I knew it was three coins before I started digging. The Ace would have only given one signal. Plus, I hate the 'ding' tone of the Ace. The Silver sounds like a cool drum circle with the choppy signals as you move thru trash but man, when you hit something good, it's like the Silver gets excited - perfectly obvious sound. It sings out, leaving no doubt where to dig.
I'm covering ground probably 10 times faster with the Silver than with the Ace and have much more confidence that I'm not leaving things of interest behind. Plus, it's just more fun.
I dug a dime at over 8" with the Silver this past weekend. The Ace never would have found it.
Oh, and the Ace is piss-poor at pinpointing compared to the Silver. I'm digging smaller holes and often just popping items instead of having to dig a plug.
Anybody want to buy an Ace? I was keeping it around for friends but I think I'll sell it and buy another Silver. Then I can run a couple of different coils when I'm out alone.