We're successful with many groups of Boa, including the
imperator subspecies. The key to this is an understanding of Boas as complex and diverse. Different as subspecies and locality of origin and as individuals. No care-sheet, feeding schedule, video-guide (or even my web-site) is more than a starting point. You have to observe your animals and use what you learn to plan for the results you want under the conditions you provide.
In my view if you are keeping your Boas alive and healthy for a dozen years and more and getting good litters of perfect babies.. kudos to YOU! not just what someone has told you.. At the same time if perhaps after some false starts a keeper is still having trouble and loses Boas to illness or accident.. that person needs a new hobby.
This link is to our integrated guide to Breeding
Boa c. subspecies.
http://www.riobravoreptiles.com/care_breedingboas.htm
Good luck!