I only knew the solution for the first speed gel test ^^ All the rest was really awesome stuff!
If I can suggest only one thing : please reaplace almost all those laser fields by grids when possible... They are too many stupid way to die accidentally ^^"

Trying to drop the cube onto a portalable surface on #3 gets frustrating and you have to do it TWICE! Could you not put a few more portalable surfaces on that floor? Considering how you get the cube, this should only make this part more manageable. After a while I was 'noclip'ing to get past that part as I knew what to do it was just doing it.

Here is the walkthrough

http://www.youtube.com/watch?v=J_iAGN-ut2A

I'm afraid that running to that gap without glass and then rushing back was like part of the test.
And maybe I should add some lights with the help of Hammer Editor, although there is enough light where needed, in my humble opinion.

Nevertheless, thanks!

The chamber could really use some more lights, though I understand you've reached the entity limit. In the room with the sphere and the funnel, the glass should be a grate, so that it is easier to redirect portals. The same applies for the other loops.