Both of them have a reasonable resale value, i don't think anything above mid $xx but i am not an expert (nor do i know much at all) about .MS
Development wise these have huge potential. I think your best two options are:
1) Play on "MS" meaning "mini site" as opposed to Montserrat and set up a portfolio,profile or similar website.
2) Use "MS" as "myspace", good names for this type of development however it has been (over) done.