I have one, a first-year 2009 model...it's kind of a unique thing, I guess.
Pretty wide at the nut, imo (1.9 inches, I think?), but narrow-ish string spacing (17mm, slightly less than 4-string Thunderbird's 17.5, a bit more than the 16.5mm on my Ibanez 5-strings).
The only Thunderbird I've owned that truly has neck-dive, but not unmanageable, lighter tuners might help.
Not very heavy overall though, mine weighs more or less the same as the other Thunderbirds I have/had.
Most folks have a dislike for either the pickups, pre-amp, or both, that were used in the Pro 4 & 5. I can get sounds I like from mine, but my plans have been to replace the pre-amp at some point; I've no issues with the pickups.
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Not sure if that answers your question, but maybe it helps a bit?