Yes, the receiver is not terribly picky on the angles it can receive on. This is no shortcoming in the map. And there are indeed multiple ways to deal with the turrets; throwing them in goo is indeed the easiest one.

Cool map! I can knock the turrets myself; and the last laser catcher can be done by putting the laser beam at side portal to hit the receiver.

Allright, thank you. I don't know of any way to fix the demos that hang the game. The hang is just temporary, and the game will resume when the delay is elapsed, but as a watcher of the demo there's no way to know beforehand how long the delay will be, and during that time the game does not react to any input and it will appear as unresponsive even to the operating system. As the delay might even be hours, there's little incentive to wait it out.

I used the changelevel command to record a new demo. this prevented me from accidentally overwriting a demo file, and it prevented me from learning about the autosaves in the map.

finale 4 ~9min: was just trying to find the end of the level.

sorry about the broken demos. I will avoid recording pause times and alt-tabs. is there any way to fix demos broken this way?

@NanoPi (2/2): Second session 3: Game becomes unresponsive at 2:33.
Finale 2&3: I had addressed the bridge lineup problem in the update. Why aren't your autosaves working?
Finale 4: Finally you realized that you can leave the cube behind and grab it when you're done with setups. Still carried it on bridges though. At ~9min: I defy you to disclose to me the rational thought behind what you were doing. Congratulations on almost reaching the end!
Finale 6: Congratulations on persevering through, and reaching the end! Any comments?

@NanoPi (1/2) Wow, that's a lot of demo. Thank you. Hmm, your demos are of older version of map (more than a week), yet you only just now released them. How odd. Here's your test results:

First session 3: The game goes unresponsive right in the beginning. Didn't bother waiting it out.
4&7: Lugging the cube on the bridge is not necessary. That's such a high-potential source of rage-quits, that I would never require the player do that. The same goes for the flings, of course. In the end of this part, you found a shortcut I had already patched, but you were playing on an older version.
5: Halts near the beginning. Demo is useless. Don't alt-tab while recording, because your AFK time will be replayed in real time with the game completely unresponsive to any input!
9: By now I'm wondering why aren't your autosaves working. You seem to be restarting from beginning each time.
12: Yes, that shortcut is possible. Hardly worth the effort, as you maybe realized.

I recorded some blind playthrough demos [dl.dropboxusercontent.com]. intheabyss* is first session, finishtheabyss* is second session.

Made a video walkthrough for your convenience

Demo for those with slower internet [www.dropbox.com]

I died many times in the water due to stupid portal placement in the water. Took me a few minutes to discover that the laser should be oriented perpendicular (I thought it didn't penetrate the glass, maybe it's my video settings but it looked like it wasn't going through).
First try [www.dropbox.com]
Second dumb try where I thought I was a smartass for breaking the game but actually I was supposed to carry that cube with me [www.dropbox.com]

FULL WALKTHROUGH (soon)