Working from the following "10-line whitepaper"

> Functional benefits for Firebird are:
> - easy: low/no admin, self tuning, single file db possible, etc.
> - scalable from embedded to high-end
> - rich, world-class feature set; innovator
> - strong developer and user community (i.e. future proof)
>
> Emotional benefits are:
> - low/no risk of failure & angry bosses/customers
> - be part of pushing out the technology frontier
> - open, international, friendly and helpful community

a possible slogan could be: "All of the power, none of the fuss"

It doesn't capture scalability and great community, though.
Also, "fuss" is perhaps not understood widely.

Looking forward to better proposals.