Totally disagree with some of the negatives I read here for Continental glue (can only speak for their aluminum rim version). I used Vittoria's mastic for many years when using Vittoria sewups and even for Sprinters. When I started using the Sprinters more and more I went to Conti Glue in the individual tubes. I could never tell a performance difference between the two brands of glud.
If you follow Continental's directions online you will not experience problems, aside from good luck removing a tire on the road (just make sure you are carrying 1 metal tire iron). I also have to think that if there is a potential for a difference in formulations, it may be best to use Vittoria Mastic with Vittoria sewups and Continental glue with Conti sewups.