Ok,
Same problem as I have posted...
So I tried the following and it worked for me...
I opened the Stable DCS...opened the module manager and removed the SU-33 module (simply because it is a smaller module, pretty sure any will do...ie used the trashcan icon). DCS turns off to uninstall the selected module. When it restarts it showed the SU-33 module and the Mi 24 module were available to download, with the check boxes pre-selected as normal.
Selecting OK to install the TWO modules...allowed DCS to COPY over both from my version of 2.7 blah beta and hey presto BOTH modules installed with no issues
This may help someone hopefully...now off to Hind the hell out of Syria...
PS, Ed have kindly replied to my question on the Hind...apparently it isn't for use with Stable and will be released in the future...ooops...works for me so...erm...shhhhhh don't tell anyone