First of all, don't be taking it apart at every opportunity. When you do take it apart, be gentle- don't bang it together. Keep the threads clean and lubed, good oil or light grease.
A loose TD can be a good bargaining chip with a seller.
If it's just a bit loose, there's a sticky around here somewhere describing how to tighten the threads.
There's no reason a tight takedown shouldn't be as accurate as a solid frame. I prefer takedowns and they all shoot just fine.
