I really like a lot of what I see here, although it reminds me more of Eric Gill than Paul Renner. But I take issue with some uses of the exterior only serifs. I’m not entirely sure it’s that they’re exterior only as it is that they’re symmetrical, both horizontally and vertically. The serifs just seem tacked on at the top of a and as the ear of g. I think that playing with them would really make this a strong face and add in the idiosyncrasies you speak of.

Other things:

•Using the serifs as the crossbar on t creates a down arrow, and it’s a distraction.
•A two-story a would go better with the three-story g.

I agree with most of what you're saying. I totally understand the down-arrow commment on the t, as well as the comment about the stories on the a vs. g, but in both cases I have to say I just personally like the look as-is, even though I can't really defend it on any rational level. :) I'll have an update soon.