It strikes me once again how stupid it feels to need to know that a function on something new isn't bugged. I don't even know any more how long the rocket launcher bugs have been classed as a known issue at the bottom of vu texts, that will be fixed at some point. You may as well take hell freezing over as the chosen point.
Anyway, with clarification of what can correctly be used together on the MF side, it would be worth considering for some, but MF tends not to do great on dps, unless I'm missing something, so the combo with lifesteal may not be very interesting - at least not together. That would make the total value of the ring lower, as you'd only be using either half of it at a time or somewhat over half. As for, what was it, regen? lol...
Still, if someone wanting to sell one does proper confirmation of it working together with pills etc, it could be worth more than your estimate, but not greatly more...