Hey Pekka,
The Bicentennials were (I think) all wired with the pickups in series, rather than the parallel config of the 60s and modern TBIVs. I haven't had the luxury to play a stock one, but folks seem to say the mids are accentuated (e.g. bit of midrange "honk") and the lows roll off a bit -if my memory serves correct.
If yours is still wired stock, you might consider building up a new TBIV style harness using the existing sidewinder pickups and see if you like the sound better.
The 76 I bought from George here years ago sounds incredible- smooth sizzling highs, bell like mids that aren't overbearing, and a solid fundamental. One of my best sounding live basses along with the Triumph and Hamers.
It has the stock pickups rewired in parallel like I described above.
Whichever approach you take, good luck with the mods!
Cheers