A delima - Kill it or don't kill it?

So here's the question -

I started a grow about 6 weeks ago in a GH six-plant drip feed DWC hydro system. There were a few glitches but everything's going pretty well still. Two of the plants turned out to be male, so I chopped them. Three are female and they're growing very strong, so much so that I have to raise the lights twice a day :).

The question is regarding the remaining one. After 17 days of 12/12 it STILL hasn't shown sex. It's also showing very little, if any, growth. Currently it's about 5 inches shorter than the other three plants, and from what I can tell it hasn't grown at all in the last week. The weird thing is that this plant is in exactly the same growing conditions as the other three. They share a reservoir so it's there's no difference in nutes. They're all getting the same lighting. Same temps, etc. A couple of days ago I carefully moved the plant over on slot so that it wasn't right next to the big girls, just in case it was hurting for light or something. That didn't help.

So now I'm thinking about just pulling the plant and running with the three healthy ladies, but I can't decide.

On the one hand, the plant really isn't hurting anything, and as long as it doesn't suddenly grow balls, there's really nothing wrong with letting it just sit there and be a plant. And maybe it'll suddenly wake up and start growing flowers and then there's that much more bud to harvest.

On the other hand, the other three are getting so big that it's getting hard to tell one plant from the other because there's so much green (horrible problem, I know lol). If I get rid of the weak plant, then I can move the other plants around in the set up so they have more grow space. This in turn could lead to even bigger plants and therefore more bud.

So, I'd like some input from more experienced growers? Do I chop, or don't chop?