I have a SF L1 from what I read it is very similar to the E1B in actual output. I use the F04 (diffuser) regularly and a have F05 (red filter).
I have found that the red filter is not that effective because there is very little "red" in the spectrum that the LED puts out. It is rather useless unless you want a very, very, low red. I would say get a cheep red key chain light rather that blow $$ on the F05.
Maybe the F06 (blue) would work better? not sure...
The F04 is very useful and does not really hurt night adapted eyes if in a location with some ambient light (but that's really not what you were asking)