Greetings,

BMC's prohibition regarding trainers is probably based solely on stationary trainers. There are some that are not. For example, Kinetic makes a "Rock n Roll" trainer that allows the bike to lean left and right similar to a normal outdoor ride. It can be viewed here (watch the video). A trainer like this should mitigate the stress to a carbon frame when doing sudden hard efforts.

My wife and I have been using our composite carbon bikes each winter on stationary indoor trainers and we haven't had any problems. Mine is a Team Fuji and hers is a Specialized Ruby Elite. However, if the use of a stationary trainer was a concern, we would consider something like the Kinetic Rock n Roll.

Kind regards, RoadLight