Some pages back there was a discussion about using spacers on a Schlumpf hub.
Yesterday I visited Florian’s factory, together with some other unicyclists, and I raised that question. Florians answer was very clear: Never use a spacer on this hub! The retaining clip can’t take the load and would be pressed against the bearings, which are again quite different from the bearings of a standard hub.
I was impressed by Florian’s quality standards. He explained the design of the unicycle hub in detail. And it looks like the next bunch of hubs will be available shortly.