I bought an Epi Thunderbird Pro IV more or less on a whim, for two reasons. First, I wanted a cheapish back up bass for my Rick and I needed a bass that I could string up with slightly heavier strings, because we play several songs tuned to Eb in the first half of our second set.
I bought the Tbird because I wanted a big contrast with my Rick.
I've been very, very impressed with it. The build quality is excellent for the price, neck through construction, nicely finished frets, solid bridge that is easy to set up and a nice neck profile.
The strap button is on the back of the neck heel as standard, but I couldn't live with the way that the face of the bass tilted forwards towards the floor with the button placed there, so I got a pair of Schaller strap locks and put the forward one on the upper shoulder, the neck dive that is inevitable with the Tbird design is there, put not unmanageable and I find that the pressure of my forearm on the rear bout is enough to counteract that.
Pickups are perfectly adequate, but not amazing, and the pre-amp is quite hissy if you boost the treble too much...better to cut the bass and turn the volume up.
Only you can tell whether a Tbird is for you but if it is putting up with the quirks of the design are easily overcome.