imho, and nope, i have no experience with the px4d
but from the picture, as long as theres a input and output, the thing can be connected in between effect chain and anywhere.
BUT
there wont be stompswitch to step on/off and selection of functions aint suitable for stomping usage. The thing is design for table top usage. To use it as a "on the floor" effect, there be inconvenience i guess.
A floorbased multiefx wud be more suitable.