mike.e,
4 pi-pro using JBL 3677 cabinets(meant as surrounds in IMAX theaters), I just put my crossovers on top with push-in terminals for quick change of horns/drivers so I can make comparisons quickly while the previous horns image is still in my mind. With the Pi crossover, the resistor network makes it easy to disconnect the horns without tunring the amps off as it loads the crossover when the horns are removed.
As long as you don't short the wires coming from the crossover HF output there is not harm to anything.
Disclaimer: Don't do this on any other types of crossovers, especially 2nd order as this could cause problems back to the amp.
Ron