I was not sure which sail you were suggesting for my girlfriend and since I could not find any Retro or NCX in 4.2m size, I went to the Severne site and compared weights and noticed the Gator was lighter than the NCX and offered in 4.2m. So I was actually comparing the Gator with the NCX, not with the Retro.
I just checked the Sailwork Ripper and it is very light. I will try and see if I can find it in my area.
Thanks for the help.