The Bophe projects to-date (Finger & I'm All Yours) have little or no dialogue, so writing scripts didn't seem necessary. For these first two, we did write out a general sequence of events, but these documents were nowhere to be found when it came time to shoot. I guess we had the visuals pretty much memorized so we didn't need it written down. Not having a script at these shoots did not present a problem. Although we did have some challenges with Finger (complicated makeup effects), I don't think a missing script was at all to blame.
Our next project in production, Closet, is the first one for which we have written a full, formal script. Vicky Bunczk bought/read a book on script editing, then took the dialogue and action that Charles and I wrote and converted it into a "script." It was a wonderful job! This shoot has been somewhat problematic for us, but again, I don't think the script has anything to do with it. The action is much more complicated than anything we have previously tackled and we really needed storyboards (among other things...). So...we got storyboards done and we plan to go back to shooting later this year. When it came to the dialogue for Closet (the dialogue portions are already done), we took the approach that certain key words/phrases/ideas need to be conveyed in order to get the point across, but we gave the actors creative leeway to improvise the line -- as long as they remembered to cover the basic story elements that were important to the script. This allowed for a more natural performance from the actor.
We have several other projects also in development. As far as writing scripts, for us...I think it mostly depends on what is happening in the movie. If the project is mostly visual, then we will likely not write a script. Charles and I work well from memory. We see certain shots/angles/sequences in our head, then try to recreate it for the camera. I don't think a script would help with that.
If the project is more dialogue-oriented, we will likely write it down but then allow for improv.