When i saw the F4 on the internet i thought it is just a repacked Discovery 3300 or Titan 3000. I was wrong. I got one of the first F4 and read on a forum that the factory has a recall going on for it. I drove to the factory ( a 1 hour 15 minute drive) and they updated the F4 for me.
The F4 comes with the 11" DD coil and a 8" round concentric coil in the box for $ 425. Some Bounty Hunter coils can be used too. The 4" gold nugget coil and the 10" magnum coil.
I'm a fan of small coils so i compared the F4 with the 4" gold nugget coil with the Ace 250 with 4.5 sniper coil. The F4 airtests about one inch deeper with the 4" coil. I picked up a US quarter at 7.5 inches in air with the 4" coil. That is very great, because you get outstanding target separation with outstanding depth (for a 4" coil). I use the F4 with the 4" coil at a local highschool to see how it does. I was impressed how quiet the F4 was at max. sensitivity and how many coins i found at a place that has been hunted by many local detectorists. Coins at 6" in ground...no problem. The motion All Metal Mode proved how close some trash items were next to the good coin signals.
If you put the 8" round coil on it you can pick up a US quarter at about 9.5 inches. Pretty good for an 8" coil. Next i tried the 11" DD coil and it picked up the quarter at about 12 inches.
US nickels will be picked up about an inch less than the quarter. US nickel are IDed great with the VDI numbers (100 !!!). Better than an Ace 250 from Garrett.
I don't really know to what detector the F4 compares.
It is better than the Garrett Ace 250. (Deeper, better ID, true all metal mode, ground balance for the all metal mode and a DD coil for bad ground).
How about the Whites Prizm line ? The Prizms are slower than the F4, the Prizms don't have adjustable GB and you can't buy a small coil for them. No DD coil either.
The F4 are not as hot as the F75 but they are in it's class by its own. They make great "do it all" detectors. I still have more testing to do but the first impression is pretty good.