IMO you are quite correct to tread carefully.
I adore the aesthetics of the Thunderbird - and they sound just great - but as much as I tried (and try I surely did) I simply just could not get on with them for the reasons outlined elsewhere on this thread (size/unwieldy etc.) Also, a word to the wise, avoid models with the 3 point bridge like the plague if at all possible; it is the single WORST piece of bass guitar hardware EVER conceived!
If you really need to scratch the T Bird itch then my advice is opt for the neck thru Epi with Gibson pickups.