Congratulations on the new bass. Now the anticipation of delivery starts.
The "decorative" dummy hum canceller was probably due to the instrument having the Series instrument preparation. Unless things have changed the Brown Bass is the only model that is thick enough to add Series electronics down the road. The Series prep adds a thicker body, dummy hum canceller, 5-Pin and other things to allow the other bass models to be converted to a Series later on. Having both Series and Brown Bass with Anniversary electronics I would not consider converting the BB. While they do sound different almost all of it is due to the woods with the electronics not having noticeable effect in a live environment.
As to whether to add a 5-pin or not I would not do it unless I knew I was going to be doing a lot of bass swapping between a Series and non-Series bass. Even then there are better ways to handle that via pedals and/or switches. If you were to add one the standard wiring used for Series instruments means the LEDs only work when plugged into the DS-5. They are not functional on batteries only. It is possible to wire things so the LEDs will work on batteries or external power but the question is if Alembic would be willing to do it and the cost if they do. From my experience with my BB the batteries for the LEDs would last at least a year with the preamp battery lasting anywhere from 6 months to a year when I was playing regularly. For comparison my Series 1 will last about 20 hours on batteries. By sticking to batteries you also don't have to drag along another piece of gear.
While we are on the subject of batteries one thing to be aware of is Alembic basses, non-Series or Series, give no warning that the batteries are dying. They pretty much go from a nice clean tone to the sound of hell instantly. To this end I would change out the preamp battery if it had been in the bass a while before important performances. I'd then use the old one in my tuner other outboard gear where I could afford for it to live out its life. To this end I've always carried a fresh spare in my case along with a full set of setup tools so I could field replace the battery or make quick adjustments to the neck or string height.
