Barber,
I've had the Quattro for about 5 months now. At first try I thought this thing was going to drive me crazy. Finally came to terms with it. The "coin garden" helps you to identify good solid tones. Plant coins couple feet apart, different depths and different coins, you'll soon recognize the difference between good hits and bad hits. Bad hits can be iron that you pull the coil up from while sweeping, or just a fast sweep over iron will read coin. Also when in coin or ring mode when you hit a faint target if you sweep it over & over the tone will go null. I prefer the all metal cause it recovers quicker from hits & repeats better. Although I haven't been to the beach yet, so don't know bout that, but supposedly that's where this thing does best.I would'nt bother with the pin-pointing in trash areas, it picks it all up!I truly believe this machine is one of the best, but really can't say for sure cause I havn't tried the rest, nor do i expect to ! look on Ebay and see how many used Quattro's for sell and compare.
Good luck,
Smartin
ps, I did read the "Mastering the Quattro" by Andy Sabisch, it's a reassuring thing to read, and has some good info. I always use the "auto sensitivity" in all metal mode!!