Mechans - it is very easy to swap out the crossover, given the new crossover is designed as a drop-in replacement (and most are). It is simply a matter of removing the securing screw on the original (screws crossover down to body of the speaker), unscrewing the wires for the three separate drivers (mark each one if you think you may get confused (not hard to figure it out even if you do). Remove the original crossover, drop in the new. Screw down all the wires to the appropriate terminals (usually well marked), and screw down the crossover to the speaker body. The AA crossover you have is pretty darn good, and I actually liked it in a smaller space. It occured to me to soften the edges a bit...a bit warmer perhaps. In the case of Al Klappenberg's crossover, the results are very pleasing in a larger space where it really draws a sharply etched picture of each of the instruments in space (this was the most apparent difference to me), and does wonders for the soundstage this way as well. The ALK, and perhaps some other options, give you an option to attenuate the midrange horn differently. This is also a fairly easy and straightforward adjustment that involves changing some wires at the terminals of the crossover. All the wires are there and numbered, and you'll have a list of what each combination of pairs will do to alter the attenuation. If you go to the Klipsch forums and search under "ALK crossover settings" you will get some idea of what folks are using. My settings will not be useful as I'm using a non-stock Fane tweeter for my LaScalas. Best thing to do is use others experience as a point of departure and see what sounds best for you. There's a few other fellows doing drop-in crossovers for older Klipsch as well. I have no experience with those, other than hearing Boa2's Khorns with a different crossover which sounded great in his system. I never heard the original to compare though he said it made a huge difference. Write to him if you want more info on the variant he used. I believe they were a bit less expensive than the ALK's. There is one guy who is building the crossovers as close as possible to original. If your AA's are working fine, I can't see any reason to go that route. Like any component, the crossovers will require some burn-in time so don't be fast to judge them if you buy them brand new. Make your comparisons with a few hundred hours on them.
Marco