At the moment it is impossible to see what the input/output speed (5/10/30/120) of the connections is without hovering over them.
Perhaps using 4 different arrows (each with successively more arrow-heads similar to fast-forward buttons - like: <-, <<-, <<<-, <<<<-) to represent the speed would be possible? That way you can see right away what each connection's speed is, and the direction will just as it is now represent input/output.

Additionally since the pipe connection speeds dont depend on how full they are (they function more like assembler's storage as they accept full speed up until they max out or provide the output at full speed until they bottom out), marking their update speed in terms of fluid/sec as opposed to ticks/update would be better? So instead of having them listed as 5ticks/10ticks/30ticks/120ticks you instead have it listed as 30k/sec / 15k/sec / 5k/sec / 1,250/sec fluid throughput.

I really liked these suggestions when I first read your thread, but had a lot of issues trying to implement them.

For the first suggestion, it makes sense to be able to see the transfer rates at a glance.
There are several problems:
How would "balance mode" work with this system? It would be too cluttered if the graphic looked like <<<<->>>>
Belt and circuit connections don't use a tick based update rate. Would these just use the old system? It would probably clash between old and new
Chest connections have 5 distinct update rates. From 5 ticks to 600. I think it would look quite silly having the connection look like <<<<<-

For the second suggestion:
Every fluid connection setting combination is actually a unique entity. It's impossible to edit entity descriptions during runtime.
Some mods such as bob's logistics can add 50+ pipes, fluid tanks, underground pipes, pumps, and other fluid entities.
This suggestion would require me to create a new entity for every combination of these fluid entities, leading to an exponentially huge number of entity prototypes.

How about changing the color of the connection Indicator?
regarding colors, how about 'linking' them to belt colors yellow, red, blue, (and modded) purple and green (longest update rate yellow, shortest update rate green) .

It would be trading one source of information for another.
I have a feeling that most connection indicators would just end up looking exactly the same.

I second Marius8's option - currently the colors are used to represent the 'type' of connection which is a bit of a useless bit of information seeing as how you can infer the connection type from which entity is used to make the connection (belt/pipe/chest/combinator/heat pipe). Using colors for speed would make more sense and prevent the issue with over-cluttering the image with too many arrow signs (I tried drawing some arrow signs in gimp as a proof of concept but quickly ran into the issue that 32x32 pixels just arent enough for more than 2 overlapping arrows without being too cluttered).
You can also use the white color to denote connections that dont have a speed variable (belts/combinators).

The other alternative would be to include numbers (or roman numerals) in the image, but that also runs into the same 32x32 limitation in addition to being hard to discern when you zoom out.

In terms of most connection indicators looking the same - probably? In my current playthrough focusing on a megafactory-in-a-box recursive play 90% of all connections are of the slowest kind (120) simply because I dont need any more than that so hopefully that keeps the UPS hit low. In only a few specific situations (chest connections in the mall zone and pipe connections in A&B rocket fuel production mainly) do I need faster connections of 30/10. But at the same time I have been having trouble with blueprinting the designs to a book and pasting them with the connection settings so my typical build process is walking into the building, pasting the blueprint, letting my super fast robots place everything from my inventory while I check every single connection by hovering over it and setting it as needed. If it was possible to just ensure the connections are all good visually that would be much better.

For the second suggestion... probably as you mentioned - not quite workable.

Should mention that 32x32 is not a hard limit. Very simple to change the dimensions of that image.