I think the SIACE Superlights appeared not too long before New England Arms closed its doors. Don't know whether that had anything to do with the guns' success, or lack thereof.
The guns were never "cheap" and there were some reported reliability issues. I have a friend who owned 2....both guns developed ejector issues, one broke a top lever spring during the first season, and one wouldn't cock the left barrel. All issues were repaired and worked fine after that. Both guns were ordered Through NEA. The Legend he owns is an awesome gun. As round as a Dickson, engraved by a master (I forget who, Tomassini??), excellent wood, fit and finish way above average. No problems with that gun, he still shoots it often.
I don't know the actual number of guns built for Dakota by Ferlib, but it seems like more than just a couple. I've probably seen more than a dozen for sale over the years. Same with Dakota Superlights. I'd be curious where JR got that interesting nugget of info.