I have to reply to your good question with another one: what kind of remix are we talking about?
Is it only intended for record release and airplay? Then yes, it is safer to have it mastered.
These days you can get a song mastered for very little money, and if you like your mix, you owe that to yourself.
Is it dancefloor-oriented? If so, you need to verify that when played VERY LOUD, your mix retains power, punch and clarity.
Most DJs wont play your track, as good as it may be otherwise, if it requires making too many EQ corrections on the spot... there is just no way around this.
Since the levels better match other remixes currently played in clubs... by all means, if you're not too confident in the overall EQ or loudness, get it mastered.
In this case though, you'd better find a mastering engineer who specializes in EDM, since it involves a particular handling of the treble and bass ranges. Dance-oriented mastering suites often use huge club-like sound systems besides the usual high-end amps & speakers.
The alternative being to put another remix of the same genre in your DAW and compare, using your ears AND a spectroscope.
Hope this helps.