My husband doesn't like triples at all and always tells me not to let anyone convince me otherwise. He says they have more shifting problems, i.e. don't shift as smoothly and/or chain comes off ... much more often than a double or compact double.
Has he been talking to my husband? Mine doesn't like them either.
As to the different levels of carbon, my 5.1 is Trek's white OCLV. It is really, really nice on these bumpy roads. So much gentler than my steel bike.