Mhhhh...
First a separate texture is against optimisation, the more state change there is the more work your graphic card do. (Of course one more texture.... well you know, the ShuttleA have 10-15, this is not the example to follow and some worse model are exploded into 40-60 textures. The UMmu have yet... one texture, so one more would not do an enormous difference but alla, loosing CPU cycle must have a good reason, so here come the second one
Second whatever system there would still be one texture per MMu type with logo. So editing the big texture with logo or a small one with only logo is strictly the same work.
Okay, OrbiterSound released, time-line is:
-Finishing of UMmu 2.5, test, release.
-Test of UCGO & DGIV-3, release.