You know, the funny thing is, I thought the life-steal ring would be useless at first, but after seeing it in action, I realized that it's basically pure DPS as long as you stay close to you opponent during a combo. The extra damage ranges from about 500-1500, plus Hazama gets his CS meter gain back during OD.
Thinking about it some more you'll realize that you forgot to mention the fact that that particular combo also has a Heat gain of 30, so Hazama still ends the combo with more Heat than he started it with.