I've yet to use this armor due to the fact that I read on the Fallout wikia that it's glitched. Apparently, according to the wikia, if you complete a quest that affects your reputation with any one faction while wearing this armor, your reputation with all factions will be reset to "neutral". Link and quote from article below.
■This armor has a faction bug. Whenever you gain fame or infamy while wearing this armor your normal reputation will be reset, leaving you with only the reputation you have just aquired. However, if you still want to wear the armor regardless of the risk here is what you have to do.
1.Save your game.
2.Whenever completing a mission for a particular faction DO NOT WEAR THIS armor. Switch back to a factionless armor when gaining fame or infamy so that you dont gain any reputation while wearing it.
3.Whenever fighting a faction, switch to factionless armor and when done switch back to it.
4.You may fight anyone with this armor that is not part of a faction (fiends).
■However; faction reputation may reset after long periods of time. This actually is incorrect in some cases, and only adds to your reputation while wearing the armor. Example, you could be idolized by NCR without the armor, but "liked" by them while wearing it.
http://fallout.wikia.com/wiki/NCR_Ranger_combat_armor