And B6 could distinguish itself on the LIM run with a lie-flat business product for a 5.5 hour+ flight, especially with a redeye return. Avianca runs MIA-LIM on an A330, AA & LA use 767s & Spirit runs their craptastic product to FLL as B6's only direct competition. I know I would pay to avoid having to use MIA as my airport and for a reasonably priced business product. Connections and Immigration at FLL are easy and plentiful (not as plentiful as MIA but I dislike their immigration experience).
If they have the demand for seats that would make the flight with a business product worthwhile routing a plane fulltime for the flight may be worth it and can run 1 flight to JFK & back between LIM runs.
CO used/uses the 752 on the EWR-LIM route for fleet utilization purposes and also to compete against LA's business product. If CO used a lounger business product they wouldn't be competitive. The load doesn't demand a 767 but the 752 fits range, seat requirements and cargo loads.