"I would really like your thoughts on just the bug-net (inner modular) setup."
What sort of thoughts are you after? The inner would set up easily like this and work nicely, but you would need add the ridgeline guylines to it (or steal some off the tarp) because when you get the Echo I there is just an empty LineLoc3 tensioner on the front, and on the rear there is the short bungie cord to clip the inner to the tarp. So plan on spending 2 min adding guylines to the inner before you can set it up by itself. It makes sense for HMG to leave these guylines off because you wouldn't normally want an unneeded guyline just hanging in the doorway and at the rear they need to attach shockcord for clipping the inner to the tarp for the normal setup.
The process of adding the tarp in the night seems a bit slower than just adding the fly to a tent, because to set up the tarp you need to space the hiking poles further apart, so essentially you would be starting the setup over. I will use my Echo I in inner only mode, but likely only on fairly warm nights with close to 0% chance of rain, so there is little chance that I'll wake up when it's raining and need to spend 5 minutes re-setting up the shelter.
"I am also curious if a foot-end beak is available."
The tarp is about 2 feet longer than the inner so you get about 1 foot of overhang on either end (plus the beak on the front). You can shift the inner closer to the head end of the tarp to get that foot end overhang closer to 1.5' if you want. Accordingly, rain getting inside the inner isn't really a concern. It would have to be blowing nearly horizontal to get in. Even then the foot wall of the inner is waterproof cuben material so that would block most of it. Some wind could get in if the foot end is facing into the wind, but normally the foot end wouldn't be facing into the wind and even if it was, the solid foot end wall does a pretty good job of blocking it.
The only situation in which I would prefer to have a 'foot end beak' or wall is when I'm using it without the inner and I'd like the psychological advantage of feeling fully enclosed. I don't sleep well when I'm thinking about how a bear could just poke it's face in the open end of my shelter and munch down on my feet. Even though I know this is an irrational fear, I sleep better when I'm fully enclosed. I haven't used my Echo I without the inner yet, but my plan is to lean my pack against the foot end trekking pole to largely block this opening. You could do this too with or without the inner if you were worried about wind coming in the foot end.
If you want something similar but with a close-able foot end, you could look at the SpinnShelter from Gossamer Gear. It's similar to the Echo tarp+beak but it's all one piece instead of two and it had a foot end wall that velcro's into place. You could use this shelter with a inner bug tent like the ones sold by AlpinLite Gear. The SpinnShelter + Alpinlite Bug Shelter 1.25 is a nice combo, but personally I strongly prefer cuben over spinnaker so that advantage plus the additional modularity of the Echo is what drew me in. I also like having a 1.5oz cuben floor rather than a less waterproof, less durable and slippery silnylon floor that those Alpinlite bug shelters have.