according to doug oade, you should not need the basket shockmounts for the u89's in normal usage. the capsules are internally shockmounted and that should be sufficient in normal circumstances. certainly, shockmounts could be used as anadditional security, but, imo, the neumann mounts are way too big and are extremely expensive. they are like a 4 inch cube and two of them take up an awful lot of space. plus at like $250 each, they are pricey. (however, i still have one that is unused that i was unable to sell if you are interested in it...i never tried hard enough to sell it).
as for m/s, x/y and blumlein configs, who was it that used to modify shure vert bars so that LDs could be run in a coincident pattern vertically? I would think that would be the ideal option as you could almost ensure that the capsules will be aligned using the modified vert bar and 2 neumman swivel mounts.