What is the minmimum room size for Magnepan?

I know it will depends on the model, the bigger requires the larger room. As the speaker require to be quite a bit far from the wall. What are the minimum room size it requires (esp. for model MMG and MMG 1.6) so it will let the speakers sing with thier full potentail?

Also how durable are these type of speakers? I mean how long I should expect them to last? I have heard about scary stories that the the ribbon/quasi-ribbon types fall apart easier/faster than the convensional ones. Is this true? Anyone have had a real bad experience about this?

Thanks a lot

ake