Hello Eigen,
On the heels of the last comment, I wanted to (cautiously) offer a thought... if there were a "Donate" button on the Eigen home page I would click it today.
Donations could be used to sponsor a traveling university fellowship or student stipend for dedicating work on Eigen bugs and features. This might help make the 'sponsorship' comment very easy for the individual as well as organizations to contribute toward. Managed by the core development team/administrators, a sponsored position could accelerate/focus work as administrators see best. For individuals like myself who use Eigen heavily but have not made meaningful contributions to the code base, this could be an avenue we could help support.
I sincerely apologize if suggesting this is in any manner poor taste; it is not my intention to offend. I can appreciate the downsides to proposing any kind of financial aspect to the Eigen ecosystem.