Nobody uses them at the top level but I still think they are an effective play. If you have a dominant fakey push and a pin pull, well the rest is left to imagination,,
I still see the heelshot fake into a push, and a lot more often, that just seems naturally to square off, because of the 3x-4x longer brush on the ball during the backswing from the frontpointed position, adding more friction on the side of the ball, creating more clockwise sidespin, enough to turn a natural hard slight spray push into a pounding long square push. I guess the fake heelshot into a pull is less natural and I more often see a standard quickset palmroll pullside from the middle, using a return or brushing motion to square off the ball instead. And that variation's very effective, especially with a lot of snakers who decide to quickset a palmroll pullside while faking or "selling" their move to get into rollover position.
Perhaps the backpin fakey pull could be as natural as the heelshot fakey push, but I guess a lot more backpin players just naturally go pullside with a standard brushup firing motion, even way way beyond deadbar. That natural deadbar rightside pullside with the natural return motion into a brush, while firing, just seems so much simpler from the backpin, anyway.
I also still see a lot of transfers from the middle (32 man) heelshot set, back & forth, to either outside player (31 or 33) and then quickly turning it into a slice or angle shot from either outside player figure, and usually with a palmroll shot. Or a quick dink from the outside into the corners. It seems to be just a variation on a 3player tic tac on the 3bar, culminating in a slice palmroll from either the 31 or 33. In comparison, I don't think I've ever seen a backpin from the center transferred repeatedly to either outside (31 or 33) player and then shot from there, with wrist or with a palmroll.
The main advantage of the heelshot, or frontpinned, ball shots, of course, seem to come from the natural ability to roll off the frontpin or heelshot at a 45 deg angle and shoot a square or high angle palmroll quickset. With the backpins, more effort and rhythm is needed to get into any desired firing position, plus the longer distance to the goalmouth, of course. One major example is the straight or quickset. Any decent series can move the ball in a pin, but only the heelshot ones allow one to leave the ball to stop, come off the heelshot pin, and almost immediately strike the ball, square on, or at any angle. This seems nearly impossible to easily do quickly enough, when using a moving backpin series. One just needs to move the ball on the heelshot, leave the ball alone to stop at any position and come off and instantly wrist flick or palmroll the ball. This is just so problematic when trying to come from a backpin series.