I plan to keep the Legacy bases with all of it's connections attached to the control center I am building and not remove it for upgrade downloads as infrequent as they reportedly will be. I intend to connect a serial splitter to the base, one end for connecting to the other Legacy/TMCC needs and the second end will have a USB adapter which is pretty small/inexpensive, that I purchased. The USB cable will be attached, when there is an upgrade to downladapters.
I plan to leave the "black" module in the base all the time. Is this an issue?
Are there others steps - buttons to switch on the base's underside, etc. - not identified in the manual I need to think about and plan for?