I would suggest that the MH-6 has incrementally adapted to modern military standards during its service life in such a way that would make them essentially wholly different aircraft than the original OH-6. But I’ve never worked on either so I don’t know for sure.
I also think there’s a valid point to be made(that is being made?) that a product that was designed for civil use vs a military application will be quite different. Even though these aircraft won’t be in combat per se, they would ultimately benefit from whichever manufacturing standard produces the most rugged and reliable aircraft for the best price.
The other aspect SASless pointed out regarding the 4000ish H-60s in use worldwide is spares availability. Granted, not all of those are in the latest configuration but the supply chain isn’t going anywhere, these aircraft are going to be in service for many years to come, with new users adopting the platform nearly every year.
I’d like to add at the end here my firm belief that an H-60 variant used in an application like this for a few hundred hours a year and possibly hangared substantially more that an H-60 in military use, would therefore be substantially more reliable as it was originally designed to live its entire life outside, exposed to the elements.
FltMech