Already owning a Sire V7 Vintage 1st generation and a Tanglewood Rebel fretless I was looking for a better quality budget fretless bass and based on my experience with the V7 and after doing some checking on the internet I ordered the U5 Natural Short Scale Fretless. Short Scale because of the tone and also playing comfort, I have small hands. I own it for about three months now and I'm impressed how they can make such a bass for this price; I used to own a Music Man Stingray so there's the reference ( which was sold because I didn't play anymore back then...stupid...). The build quality and finish are very good, the sound is warm and round ( I use this bass for ballads and easy listening pieces) but can also be very bright; the pots for the P/J pickups and the tone control respond well and have a solid feel. Playability is very good but you have to get used to the fact that it is a short scale. Although it's more comfortable for my hands it took some time to adjust to it. Set-up was perfect when I unboxed it, the action is a bit high but that's how I like it. The standard strings are not that good. It was quite difficult to tune the A and E. The bass is now equipped with LaBella 760FS-S, tuning and tone improved significantly. Tuners are better than on my V7 but in my opinion, the tuners are the least good thing on a Sire. You can tune perfect to the tone but the "feel" could be better; my cheap Tanglewood has better tuners than the Sires. The balance when played sitting or standing is perfect and the weight is, compared to the V7, an improvement. The rolled "fret"board is nice but I wouldn't miss it if it was not so. The looks of the maple top on my U5 is quite diiferent then what you see on pictures. It's not ugly so I have no problem with it but it's.....eh...different. Keep this in mind when you order online, it can be a surprise.
Conclusion: If you are looking for a budget short scale bass I can only recommend that you try the Sire U5. I don't know if you will find anything better for € 537,-.