I understand that the unlumed yellow UTC hand on these models can be "quick-set" - ie, the hour hand can be adjusted without stopping the watch. This is a very useful feature to have (my Revue Thommen Classic Airspeed Quartz chrono has the same feature) when travelling, since there is no need to lose the accuracy of the watch when adjusting for new time zones.
The trouble is, of course, that UTC time does not change when travelling; local time - which is indicated by the normal white lumed hour hand - does. But adjusting for those changes means stopping the watch. Fine if you have another watch you can use to reset the Sinn with...and at present with no UTC hour hand on either I sometimes wear two watches when travelling, to keep track of local and destination time. But the point of having a second "UTC" hour hand is that it obviates the need to be such an obvious "two-timer".
Would it be possible to have the factory, or alternatively a watchmaker, swap the UTC and the conventional hour hands around, so that the main hour hand could be reset without stopping the watch and the UTC hand was left set to the reference time zone?
The only downside I can see to this is that it would no longer be possible to hide the UTC hand behind the normal hour hand when not required; it would instead sit on top of it. The best solution would be for the factory to change the spec so that the normal hour hand can be reset without stopping the watch and the UTC hand could still hide behind the normal hand - but I imagine that would be harder to bring about...!