If you take the time to rewrite your content you will be fine. There are a lot of tools out there that can help you to speed up the process. I also use a lot of "PLR" or "white label" content, but I rewrite it until it's at least 75% unique. I use Copyscape to check the "unique" score, and also to find out where else the original article has been published (in its white label form).

I have a really great piece of software that I use to help me speed up my rewrites. It's called "Speed Rewriter." You can do a Google search and find out about it. It's not very expensive, either. I think I paid around $10 for mine. Also, you do not have to download and install it on your machine. It runs on the net, so you just log in and start using the software. At any rate, it cuts my rewrite time in half at least.

It might be worth looking into.