I don't think tanks will be a good build after the update. A maxed tank will have the same combat level as a maxed main. Most of us haven't gotten used to pking in the beta, so we wouldn't know any more than you. All players with an existing subscription can try the beta out. To add on with what everyone else has said, prayer, summoning, and constitution will not level your character. One's combat level will be based on your highest skill + defense level +2, so the maximum combat level will be 200. If you're a pure, I suggest you train your attack and strength now because after the update, training will be more difficult. Good luck.