Get the 18mm or wait for the 27mm?

Bear with me for another lens advice thread.

So, I've completely downsized my camera and lens collection and currently only own an X100 and X-E1 with the 18-55mm.

I've had the X-E1 for a couple of months now and I've spent many sleepless nights pondering on my first prime. Now I love the 23mm (35mm equivalent) focal length - obviously from the X100 - but that lens is going to take a while to appear and for me it would be way too big.

I need a portable lens for street shooting with my X-E1.

So question here is whether I should grab the 18mm or wait for the 27mm. The 18mm is a bit wide for me but is faster than the 27mm and it's also here now. The performance/sharpness of the 27mm is obviously a complete unknown. I've also considered the 35mm but not really as portable and too long.

What do think? Would love to hear some opinions that would help me put things into perspective!