I have been using the play style you describe in this guide for the past few days. I finally got comfortable with the amount of damage Chen can soak, and realized the best way to play him was not as a traditional tank, but as bait. Mid to late game, a regen focused Chen becomes a wonderful lure where you can goad people into diving, you run away a bit and they chase, and as they chase you regen. Once you get far enough to drink w/o an immediate stun, you turn around and kill them. I'm now only suffering 2 deaths per game (7-8 being normal on most teams I've seen), and scoring 14-24 takedowns. A takedown to death ratio of 7:1 - 12:1 (average now is 10:1) is awesome when it comes from a objectives / positioning standpoint. Just being able to stand in lane for nearly the full game tends to win the XP war.