I would post on the Bullseye forum. They are interested in user experiences and they like specific details (temperature, times, colors). Sometimes the response takes a little while (maybe a week) and sometimes the response is within a couple of days.
Yes, there are combinations that might be expected to crack, and Bullseye has videos that show that in fused pieces. I'd expect there is an article on it, but I don't remember which one. Try this one:
http://www.bullseyeglass.com/methods...torchtips.html
Bullseye forum:
http://www.bullseyeglass.com/forum/i...9ccc855546b387
Bullseye articles:
http://www.bullseyeglass.com/methods...-articles.html
There is a little bit on compatibility and torchwork here <
http://www.bullseyeglass.com/methods...eye-glass.html >, but nothing specific. This seems to imply it is not the annealing schedule, but the processes during bead formation (along with the glass type, soft/runny vs. hard).