Only half the coil works in pinpoint (DC or all metal mode); the entire coil is hot when doing a normal search (discrimination or AC mode). The XLT has a toggle to make the entire coil, or just the front half of the coil, active in pinpoint, but the Classic, the IDX, and a couple other 5.9 KHZ whites machines do not. As for hunting in trashy areas, you simply cannot beat a bigfoot. Remember, it is essentially a 3 inch coil in one direction. And if you're in a really trashy spot, it's possible to tip the coil up and hunt with the tip only - making it a 1" x 3" coil. As for the back half of the coil not being hot during pinpoint - I prefer it that way. Although I use an XLT and could turn the entire coil on in pinpoint, I find pinpointing with the front half of the coil ONLY to be an advantage...get a beep in AC mode, squeeze the pinpoint trigger, and back the coil up while zigging a little left to right - use VCO so you can hear the target frequency rising as you narrow down your pinpoint - keep backing up the coil until suddenly you lose the tone - your target is within a half inch of the center of the front of the coil.
The only problem you may have with the bigfoot is that while you're in pinpoint (squeezing the trigger) and backing up the coil while sweeping a little back and forth to keep the target under the coil, you may pick up a second target - and wind up digging the wrong target unless you recheck in AC mode before you dig. I have the 5.3 black max coil, the 800 coil, and 9.5 inch coil and the bigfoot. The bigfoot, for my money, is hands down the best of the bunch. Unfortunately, the gentleman who manufactured the bigfoot coils, working with Jimmy Sierra, passed away. A new manufacturer has attempted to take over production, but is not having much success. There are very few being made, a very long waiting list, and the coils, if and when you get one, are problematic - sometimes they work and sometimes they don't.
To make a long story shorter, though, yes, the bigfoot made for the XLT will work on the Classic, the QXT, the IDX...and is better than the stock coil. In addition to being a super coil for trashy areas, don't forget that it sweeps like a windshield wiper, clearing a foot and a half width at a time....
