An update :
Three issues have come to light :
1. Some icons on the server may not display. This is an OS bug that I have reported to Apple, and that report has come back marked as Duplicate, which means other developers of other apps have the same issue. Apple have confirmed a fix will be forthcoming, but it could be months away, so I have coded a work around in the next update which overcomes the problem. In the meantime, uncheck the 'Icons reflect permissions' option in the Interface panel of the Preferences and the problematic icons will no longer be used.
2. Crashing on right-click. Every case I have seen of this is caused by 3rd party Contextual Menu plugins which are incompatible with 10.9 or are corrupted. Re-install or remove contextual menu plugins to fix the issue : this is *not* a Yummy bug or an OS bug.
3. On retina displays only, I've observed sluggish icon display performance from the OS on the Mac view side of things where there are non-standard icons (e.g. generic folder/file icons). I'm still investigating this, but since the (apparently re-written) Apple Icon Services framework seems buggy in general, I'll bet this is another bug in the OS *sigh*