Well, with fast track I manage 9,000 xp on SO and 4,000 ish on Matchmaking. So, it's a bit OP, but your rank doesn't reflect your skill, so I don't have a problem with people farming SO. I, personally, farm SO. Not for the xp, but for the commendations. Sure, the XP is a bonus, but my plan is to just shoot to 130 and then go for commendation completion (Yeah, that will take a long time, I know. And some commendations I won't want to go for anyway, so not full mastery of everything) because that way you get the xp aspect of the game out of the way and get straight to the fun part, because it's better when you don't have to worry about ranking up, you can focus on playing well.
Good day.