Official comment
What's interesting about their product page is nowhere on the page or on the linked spec sheets do they mention the drive's rated write speeds -- not even once.
One thing I found online said they were maxing out at 50MB/s, but I can tell you that most drives write slowest when handling many small files, as one would face with a large rekordbox export as the album art, waveform data, and cue information are all stored in relatively small files. Even an expensive drive rated highly for data write speeds (the Kingston HyperX Savage USB 3.1) was worse than the cheapest SanDisk drive that you could purchase at Office Depot for $6 when it came to writing the small 4k transfers.