So, my question: Can the 2 pi and 7 pi bass unit be seemlessly combined? If not, what modifications (other than crossover, thats the obvious change) need to be done to make for a good transition through the overlapping regions of the audible spectrum.

Since the setup will be located directly in the corner, I was thinking that I'd want the 2 pi to roll off the bass a bit sooner than normal. Also, is there a different driver for the 2 pi that may be a better match to the Stage cornerhorn. Would the Delta 10 work in place of the Alpha 10? If not, what would be the best match for the Omega 15 and DX25 (assuming the Alpha isn't the best match)?

I was going to build the 2 pi portion first and then build the bass units later, too spread out the cost. But, I'd like to build the crossover once, maybe with some build in configurability for pre and post 7 pi.

But I think the π midhorn on these looks great. It isn't as imposing as you might think, particularly since the system is in the corner. That always seems to make a speaker much smaller than it really is, because it is out of the way. I think your wife would fall in love with the looks of it if she saw it.

The crossovers are similar, but the current version for the one with the midhorn is the best. Every subsystem is optimized so that it takes full advantage of corner loading, and crossover is seamless at each point, using a minimum of components.

Active crossover / bi-amp would be a very good option.

I thought the 2 pi would be the right fit since the 2 pi and the 7 pi both had 10" drivers.

Also, I was hoping to create a lower cost solution, that could be bought/build in stages.