So you are basing the SE-IR being cheaper by counting it as a part of the hour building? Surely they won't be PIC hours if that is the case?. I also think a lot of people do hour building in aircraft that are not certified for IR flying due to cost.
That certainly isn't a path well tread either. You're right that for most people, it would doing a non-integrated course it would be hour building, then the CPL/ME-IR and then straight to the MCC/APS. It'd be interesting to see more information online from anyone who had done it. I had a bit of a Google and couldn't find anything.
I am definitely intrigued by this just costing £2-£3k more than the basic hour building price though.
I think your three advantages are very real too.