I have sent a few watches for service with them and every time I have been impressed.
I sent a U1 back with a bezel that had a horrible action and was able to be moved clockwise . I bought the watch new and it was out warranty and they repaired and replaced it free of charge. Their view was that it was a fault and it should not have happened so repaired it.
Sinn could teach some of the big boys a thing or two.
The service pouches are great as well, they are prefect for keeping sunglasses in.