Great post. Consider the following changes to the Greek mapping to be consistent with Greek keyboards and the "greek" input mode in Emacs:

    q Q: ; :
    w W: ς Σ
    y Y: υ Υ
    u U: θ Θ
    j J: ξ Ξ
    x X: χ Χ
    c C: ψ Ψ
    v V: ω Ω