I just found this mail from Carl Dennis whilst clearing my Inbox. I hope it is still relevant news for you all:
Just heard from Tony at Hannants that Humbrolís new decal solutions are not compatible with Tamiya acrylic paints & will dissolve the finish. Works OK with Humbrol, Revell, Extracrylix & Vallejo + all enamels.
MAFVA Nationals Sunday June 16th, IWM Duxford