Onthebumline,
Some of your comment I agree with. Your experience is similar to mine. I think that conversion could be as much or as little as you like for an experienced SH pilot. Competence arrives at about the 100 hour mark in the MK3 for the experienced crossover pilot IMHO. There are of course significant airframe and cockpit differences that will sap ones capacity, but after that it is just a helicopter....
The trouble is that we now have CI defined syllabi for arctic, desert, jungle etc that sap even more hours. The Merlin conversion in terms of ac hours is significantly less than 80 hours for the RN. The sim heavy course is probably a bit of arse covering by the system. They don't want you getting the lawyers involved when you stand up in court and claim that you had never seen that emergency before. The reason it has taken up to 10 months is due to airframe availability.
As I said, conversion is what you want it to be. Not going down the wrong part of the FRC when you are below icy cloud in poor vis at night and making the wrong decision is competency and captaincy