It really depends on how memorable that phrase is as Reece stated above.
For a company named Ribotechnik Machine Industries I would get RMI rather than the long one, as it is not memorable and RMI would look much more professional.
Few people would search for that phrase.
For generic type domains, I would go for longer names, they are also better in SERPS. I have even 5 word domains in .com ... simply because they are searched. Decide for yourself, for a business selling Ceiling wall mounts, what would be better CeilingWallmounts.com or cwm.com ? I go for the first one.