I'm trying to design comment system for my reddit-like site.
I like hierarchical comments because you can sort them to quickly get the best comments for large threads. Unfortunately with hierarchical comments sometimes you have cases when there is long thread and if you present hierarchy using indents you have a problem.

I decided that hierarchy is important only for levels 1-2, after that discussion takes place usually between 2-3 people, and regular flat comments works the best there.

Below (level 1 - comments #1 and #5, level 2 - comments #2,#6, level 3 and more: comments #3,#4)

I'm using colors to seperate hierarchy levels and +/- icon to open/close comment branch (it closes all childs). Take a look at the mockup below. Do you think it's intuitive? Or the indents are the best option to show hierarchical comments?

![Hierarchical comments](https://i.stack.imgur.com/0qBVn.png)