Just bear in mind, PVC pipe joints are not capable to handling internal water pump, which many are installing these days. The pipe isn't the problem, the joints are.

Let me clarify, the thickness of Class 6 PVC Pipes is not the issue. The joints which uses glue are the culprit for leakage. Glue type joints are not capable of handling high capacity water pump. The failure may not be instant. It may occur few months or years down the road. But hacking and replacing leak pipes will be a headache, especially if it is in the toilet where the wall are all tiles.