In addition toI have several of the Sanyo ones, and I cannot recommend them. They were nicely made, but there is something wrong with the bearing, and all the ones in my possession make an ugly squealing noise. They may be fixable. (Anyone want to try? Send me a message).
i had a squeaky Sanyo unit(mine was just old but really hadn’t had a lot of use) but fixed it. First tried putting thin oil through what looked like the seals to the bearings but didn’t work, so bit the bullet and took the assembly apart, take photos, have to get through the release/engage mechanism first. Put some grease in the end cap, it has a strange screw there that looks like it s to put lubricant in couldn’t get to the bearing inside the dynamo, reassembled and all is good,but possibly done only 20 km on it so far.
while the bb dynamo provides much more drag than a hub one, it provides zero drag when not engaged which for me is most of the time