So I had this feeling that perhaps one reason the overall game felt slow compared to DoTA was because the movementspeed of the demigods were slow. So I thought, How far can one go with speed in this beta.
I started a game against an AI and bought all the speed equipment there was. there are actually only 5 of them, and 2 are artifacts.
I used The Unclean as his base speed is quite high and his skills allow for extra movementspeed that way.
So after a few min this was what I had.

11.4 as base speed, I felt quite fast but not as if it was silly. So I made sure to get the journeyman's boots proc (5% chance on hit for 50% speed increase) and use my 50% speed item as well.

Which got me to 14.0, which seems to be the current cap :/
I was moving damn fast though and the game felt much more fast paced. The speed was still not silly though, just really fast.
In the end, would this be a viable build?
if you got 70k gold to spend you can get all the 5 speed equips, but just imagine what your enemies would have in terms of health/dmg at that point in game. Nevertheless its great since no demigod can run without you hitting them every sec which makes running quite impossible unless they start with loads of hit points.
Conclusion:
Speed does make an impact, especially since demigods can fire while moving compared to the heroes of DoTA who have to stop, One CAN get a quite good speedbuild at a reasonable price if you skip the two artifact items, then its just like 20k which would bring you to somewhere mid game and at a speed somewhere just below 10 depending on what demigod your using. The Pros are that your fast movement makes running back to base a much easier decision to make since you can be back in much shorter time, the cons are that you probably will lack in other areas and risk being pulled into towers when you chase after near death demigods.
Anyway, try it.
The speed feels awesome.