My two cents:
With Series I guts, I would highly doubt that the bass itself is the problem. I would think that your amplification system is likely the biggest factor here. The BagEnd 15 is surely a great cab, but that big speaker is best suited for your lower frequencies. A second cabinet, probably a 210 or something similar, would help to bring out the mids and highs. An Eden, Bag End, Epifani, or other 210 could really boost the midrange 'punch.'
If you are in the mood to totally revamp your system, I think it would be beneficial for your sound if you were to put together a rig with an Alembic preamp and a good power amp (QSC, Crown, etc).
If you like the WWoods and want to stick to a single cab setup, take a look at the 212 cabinets out there. They don't lose much on the bass end, but they can handle mids and highs better than most 15s, especially if the unit has a horn. I have an Ampeg SVR 212 which can bump some bass when I need it to, but the mids have all the punch I could ask for.
As Kayo said above, the strings have a huge impact on your sound, so that would be a good place to start, but I would expect that the problem won't be completely resolved by new strings alone.
Hope this helps!
Adam