Personally I feel like it's mostly an improvement. I can drop a single beacon down and get a huge boost (3x what it gave before). That really frees up a lot of space for other things. Usually my belt spaghetti.
![Laughing :lol:](./images/smilies/icon_lol.gif)
On the other hand, I have reflexively found myself trying to drop extra beacons with efficiency modules into unused space... and then realizing it diminishes the effect of the nearby speed module beacons. I sort of feel like the diminishing returns should be on a per module type basis. The possibly unintended result of this seems to be that I'll never use efficiency modules anymore, except for where I have the odd module slot free in assembler/refinery/etc... which is practically never.