BCC's got a reputation of being harder to care for because of husbandry that was only C+. BCI tend to fare better with C+ husbandry but will benefit from better husbandry. Overfeeding was a common problem and killed many BCC before all the information sharing we have today paved a better way. Also, some lines (locales) had a tendency to regurgitate meals. Part of this was C+ husbandry and for some debatable reason(s) Suriname/Guyana boas should be fed mice for at least the first year. I have never had a BCC regurgitate in my care...and I keep babies around until they are well started.
As far as size and temperament...BCC in my care tend to be more shy and most will do better if not handled a great deal. I don't recall ever having a BCC boa strike at me defensively after they are a few months old except when removing newborns from the mothers enclosure. The babies are little defensive for the first few months and then that fades (I actually miss the little hissy fits)...All three of the little ones I kept from this year came right to me looking for food this morning.
Size...My 9ish male is 6 feet long. His 14 plus year old girlfriend is a tick over 7. I have a couple of two year olds that are approaching 3 feet. Most BCI would eclipse those lengths at those ages...