The answer would depend on what you want to do with it. The effects on the mixer should be enough so I doubt you'd need the ones in Traktor but then again you might. I used to use Traktor prior to having a Pioneer set up but now I use RekordBox on my laptop and a memory stick. If you do go with Traktor I'd stay clear of 2.5 until the bugs are ironed out. Also, TBH Traktor made me lazy with my mixing but does allow creative mixing due to the auto sync function. I'll probably move away from taking my laptop to gigs once I finished analysing, quantizing and updating the tags with the key all my tracks.
If I were you I'd look at getting RekordBox usable again but if you do want to go with Traktor and you're in the UK I could sell you mine but it would come with the Audio 4 too which you wouldn't need