So your trading dispersion over matching timbre?
It's an assumption that "timbre" will or won't match with
any two speakers which are not identical(and even if they are identical, room interaction and angle-to-ear can still create a different sound - a speaker straight in front of you will have less high frequency than a speaker which is aiming into your ears). Having the same drivers, designer, or anything else does not guaruntee much... A horizontal MTM has its own "sound" which even on axis is offensive enough to create a brand new timbre - so timbre matching is thrown out the window without excessive subjective voicing, which is never a good idea imo.
Give me a speaker with relatively flat on-axis frequency response and a smooth tapering of hozitonal off-axis response. Such a speaker will blend better with another speaker with relatively flat on-axis frequency response and a smooth tapering of hozitonal off-axis response, even if the drivers, crossover topology, phase response, bass alignment, etc are not perfectly the same. Of course the latter scenario never hurts but yes, I would trade dispersion for many things, because having good dispersion is a big percentage of our perception of "timbre" in the first place.
On that note, I will add one caveat about my setup.
I've got my towers toed in rather aggressively in front of, rather than at, the sweet spot - about 45 degrees. I assume the losses of the nearer speaker being increasingly off-axis and the further speaker getting increasingly on-axis helps really tighten that center image as you shift seating positions, based on something i've read from wayne parham and earl geddes. I don't know if I can truly hear the difference between aggressive toe-in and no toe-in, but hey, the theory is sound so what's the harm, right?
Of course, such toe in probably only works with speakers that don't have any treble peaking on-axis.