Love the engineering style drawings but a couple of early observations on the logo:

The lack of overshoots make the n look too low and the u too high. The answer may be to round the terminals. Otherwise you will need to cut the straights off higher and lower on the n and u respectively.

I like the thickness of the space between the letters to be (or at least look) the same as the counters but I may be in the minority. Then we are talking fifth down out of the six you have provided (or is it fourth down?)

The reality is that the engineering approach may not be helping you get something that actually looks right.

Thanks Nick for your feeedback. I would definitely agree with your observations in regards to the overshoots of the n and u. I of course noticed it while engineering the mark and its grid, but did not know how noticeable it was. I think shortening the straights at the bottom of the n and the top of the u will help or fix this. I will try that out next.

Here is a version that has shortened vertical straights of both the n and u letters. I think it definitely helps the overshoot issue.

In my opinion, some overshoots are overplayed by some designers (just like some fonts are overkerned). It depends on the curvature of the curve for one thing. Your curves are quite tight so you might be looking at a little more than the 2.5 - 3% of x-height which seems fairly typical. It's gotta look right. You may not have gone far enough.

Just a thought, playing along with geometrical construction approach -

Wow! I love apankrat's idea, but it might add a bit to much playfulness to it.

I actually think it detracts from the playfulness...taking it too far.

It's nice -- but an engineered logo when your topic is spacing and kerning? Optically balancing white and black is a whole different beast.