This is based on my experience of having both micro and regular gonis: I have micro and regular gonis touching without any issues. I do not let gonis touch non-gonis. I only let gonis touch each other if they are similar in color, ie: red and pink can touch. IME, red gonis are more likely to wipe out non-red gonis.
I currently have a giant pink, long tentacle goni touching a short cotton-candy goni without any issues.