KL4 head on E1l body?

I've read here in the forums (mostly older posts) about people putting Surefire KL4 heads on E1L bodies, but it's not clear to me whether this combination works well with a CR123 primary. I have a E1L that I use and a L4 sealed in the box and I'm trying to figure out whether I should keep the L4 for lego possibilities or sell it. I don't want to get into rechargeable 123s, which is why I'm asking specifically about primaries. Some of the older posts suggested that a single primary won't work well with a KL4 head. Any ideas? Thanks.