What can I say. Beautiful instrument. Woodwork was perfect, instrument in tune and everything first class. Incredible accessories, including pictures and certificate. With most basses you barely get one or two allen keys. Now you get two allen keys, big truss rod key, separate holder for accessories, usb stick with stuff, pictures et cetera. Plays like a dream, and sounds like a choir of angels. However. It was impossible to play because of the neck dive.
I tested it for two days, in which time my arms and shoulder got hurt due to poor ergonomics from the neck dive. The neck dive for me was minus 45 degrees or even more. Instantly, when I tried it with my trusted leather strap, which is not sticky, the neck started going towards the floor. I tried wide suede strap too, which was even worse since that way my t-shirt was 20 cm below on the shoulder where it should have been due to correcting posture and the neck dive and suede sticking to shirt. I tried shorter strap, lifting the bass higher. Lifted very high, it was playable, but it really hurt my shoulder because you have to reach far with your left hand and I could play only one song at a time, after which I had to rest my shoulder. And I don't have short hands, quite the opposite. If I didn't lift it up, I had to hold it up with my left hand most of the time to get decent angle where I didn't have to reach so far. Thus, I had to send it back, no other option unfortunately.
I understood that some of these Thumbs and especially Bolt-ons suffer from neck dive time to time, but they should balance around 15 degrees up or zero. Yep, not this one, it went straight towards the floor. Check out Ryan Martinie playing his Thumb from YouTube. He always wears it higher with wide strap and he plays shirtless, most likely to avoid the neck dive as the strap sticks to your skin and you don't have to correct posture or worry about your shirt being 20 cm below on the other shoulder. Mine also had neck dive when playing sitting, so no help there. Well, at least I had this legendary instrument for two days, and if I ever get rich I'll order a Master built neck-through, as I've heard they suffer less from the neck dive issues.
Edit. Forgot to mention that the fretboard edges were so sharp and hard that it was painful to play anything that required constant reaching of strings with pinkie finger, as the sharp fretboard edge hurt the joint of the finger. Someone with long fingers may not have similar problems, but those edges are many times rounded to avoid pain.