Copyright trolls are of no great concern outside of North America and a handful of other countries.

But besides this, there are other reasons to choose a private tracker over public ones, such as quality control, retention and even community participation. But this assuming you can join a top-tier tracker. If a had to choose between a low- to mid-level tracker without too much content or community involvement and a public tracker like Rarbg that's really well managed, I'd choose the latter.