First of all, love the project. Current "chat in a channel" tools don't focus on helping to keep things tidy so Linen makes sense to me.
Just coming up to discover the interface for the first time. I already have some rants so please excuse me for being picky ;)
BTW didn't read the documentation AT ALL to give a perspective.
#1) I would have appreciated to see very clearly a switch to have the "forum view" trimming just name and first row of message, for alll the channels. Makes sense everywhere to me, not only in forum-specific-style rooms
#2) Not being able to select text and copy makes me nervous. I wanted to share some text from here to a chat, and couldn't.
The feature allowing to click and reply to the specific message is totally wonderful but you could leave the selection work as well. This heavily messes my OCD and with PLS (Principle of Least Surprise) usability-wise IMHO.
By the way, selecting text IMHO should also help me quoting it instantly, inside the appropriate thread discussion window of course