In reply to MATD 2012:
The normative shapes of letters are those that reflect consistent practice by competent writers over time. Normative doesn't mean fixed, but it does mean that when you see a lowercase alpha you know that it is a lowercase alpha, regardless of the particularities of style, weight, size, etc. I'm not talking about statistical norms in published typefaces, but about these basic recognisable shapes of letters that evolve in the maturation of the written script. There is, to be sure, a statistical element to this: a coalescing of practice such that the normative shape of the uppercase A can be said to be two diagonals meeting at an apex with a horizontal crossbar despite the variety of forms in writing and type that violate that norm. If you look at old Byzantine coins and seals -- as I've had a lot of opportunity to do over the past couple of years -- you'll see the Greek script in a state of flux, including situations in which uncial alpha cannot be distinguished visually from lambda, and in which the H glyph might represent either the vowel eta or the consonant nu, but we've long since established norms for the individual letters, and avoiding confusion is a strong motivator in the development of such norms.
My point with regard to the relationship of distinct styles to the normative shapes of letters is not that certain ductus patterns are norms in themselves but that the application of these patterns within specific styles at particularly historical moments influence what shapes become norms. The lowercase lambda is a good example: this is a shape that historically developed in styles employing a ductus that resulted in a short heavy diagonal from the lower left and a longer thin diagonal on the right with heavy terminals. That is the shape of the letter, and if you change the ductus while producing the same strokes, you end up with what I consider an unconvincing shape: simply put, it doesn't look like a lambda to me.
I note that in your new Greek you maintain the traditional ductus of the gamma and lambda, even though it violates what you are doing elsewhere in the design. Why? I presume it is because you recognise that the normative shapes of these letters are strongly influenced by how they were written by Byzantine scribes, and such is the nature of those shapes that they look wrong if you apply a different ductus. That is my point.