By fluke of circumstance I've had the opportunity during the past week to speak with a few Estonians involved in the HL process, including the Chair himself for a very few minutes earlier today. As a result of these conversations I've come away with the thoughts that 1) this currently is an ICANN driven process, subject to change and 2) we need people participating who understand how the MS process works in practice as well as in theory.
I concur with those who feel that Bill Drake, by virtue of this work within both ICANN and the wider IG world, is ideally suited for this role. For the other position I'd like to propose a new name - Avri Doria - for consideration. Avri, like Bill, brings multiple abilities to the table. She's held leadership roles within ICANN (Chair, Council, for example) and has technical expertise that the small CS contingent might find helpful. Of greater importance, Avri is a resident expert on the intricacies of the WG process and how MS works in practice as well as in theory: something I think could be useful so as to ground the high levelers into reality.