Again, this is a brand-new motor, nothing wrong with it except that I broke the axle accidentally. It's actually a warranty replacement for a motor that did fail, due to a failed torque sensor. I'm getting a third motor at my own expense to get the trike running again, but have an otherwise perfectly good motor now (motor 2) that is essentially a very expensive and very heavy paperweight now. I could have that motor repaired for about $750 by round-tripping it to HPV in Germany and back, but I think I can do so for much cheaper.
Motor 1 may have failed due to a number of causes - moisture getting in through the disc rotor screw holes because the mechanic didn't inform me I needed to plug them; or a bent axle, which itself could have been caused by a couple of things. The point is, motor 1 could have failed on its own, but it's unlikely. Motor 2 has not failed at all, the axle simply sheared when I was attempting to install it.
Generally, Motor 1 performed great. The GSD system is very quiet, almost silent. I really like the Bosch system we have on another bike, an R&M - it's insanely tough and reliable. However, the one complaint I have about the Bosch system is that it is very loud compared to other brands. The GSD system is also very torquey - I get faster acceleration out of it than the Bosch system, although that's generally true when comparing mid-drive and hub-drive systems from what I understand. Hub motors give better acceleration, but mid-drives are more efficient.
The bikebus version that I have is supposed to be very reliable. The newer canbus version, from what I have heard, has some firmware issues causing motors to brick from time to time. My mechanic has said that he's had a lot of warranty replacements of the canbus version. I'm replacing my current motor with the same one because that's the system already on the trike and I don't want to rebuild the whole thing with new batteries, a new computer, et cetera. Actually I might be able to salvage the batteries and reuse them, but I would definitely need to replace the motor and computer, at a minimum. If motor 3, once it arrives and is installed, itself fails some day, then I will probably rebuild the trike with something like an EBO kit, especially as I will be out of warranty at that point.
As far as a brand new build, I honestly wouldn't recommend it simply because GSD is being liquidated at of the end of this year. According to EU regulations, they are required to supply spare parts and service for the next 5 years beyond that, but as you can see from the email I posted above, they don't have the best service demeanor for an English-speaking DIY customer in the US. They essentially told me, "No soup for you!" They mostly do B2B, not B2C, like a lot of manufacturers. In my case, service is through HPV, not directly through GSD. I only reached out to GSD to see if they would be willing to sell me an axle directly. It seems to be a good system on par with Bosch drives, but a product is only as good as either the service of the manufacturer or your own ability to service it. I'm not aware of a big DIY community around this particular drive, as it is primarily sold B2B in big contracts with e-bike manufacturers and bike-share fleets. If you are looking for a good hub-drive system I would look at EBO or Luna Cycle as two of the most reliable. A lot of people like Bafang, but I've heard their motors burn out from time to time. EBO and Luna Cycle use Chinese systems as well (Luna Cycle even sells Bafang systems), but they themselves are based in the US so you're more likely to get good service. They will also build the motor directly into the wheel of your choice. I'm probably going to get a Luna Cycle Golden Pie v5 system myself when I convert an old 1990's stump jumper I have to an e-bike later this year. If I have to rebuild the trike in the future I'm looking at the EBO Clydesdale system. HTH
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