I have used both detectors. I really liked both of them. My buddy loaned me his F2 one day and I did pretty good with it.
I own 2 ACE 250's. Always need a back up, LOL. My first year with my ACE, I found over 4,000 clad coins, over 100 silver coins, lots of tokens and even a 6 pound cannonball, it was 10 inches in the ground. That was in 2006. I also have a Sun Ray probe on the ACE.
At the moment I am using my F-75, trying to better myself with this detector because I'm heading for Virginia to hunt a CW site. Not sure the ACE will work in the HOT soil conditions in Va. But I will have my trusty ACE 250 with me, just in case I need a back up detector. I'll also have a Whites XLT with me.
Some people have a hard time pinpointing with the ACE. All I can say, is every detector is different and you can't just take it out for an hour or so and learn it. I hunted all year with mine and became pretty good at pinpointing. I could even tell when I got a silver signal. I like to hunt in all metal, if there isn't a lot of trash. I dig every signal that falls on the right side of the screen. Best bet is don't use a lot of sensitivity. Guys try to turn up the sensitivity and get all kinds of weird signals. Turn it down, go slow and have fun.
Good Luck with what ever detector you buy. Read the instructions and practice, practice, Practice!
Lay some coins down along with some trash items, see where they come in on the coil.
HH,Ringfinder