Recommended prime lens for X-Pro 1?

Hi everyone, I just picked up a used X-Pro 1 with the 18-55 f2.8-4 zoom a couple of weeks ago as my everyday camera. I find the kit to be remarkably versatile, plus with the latest firmware, it focuses decently fast.

I'm just curious though, should I invest in any of the primes? About the only reason I'd want one is because the kit protrudes out significantly when using the OVF. I like the small form factor of the 18mm f2, plus 28mm is my best and favourite focal length. But on the other hand, the 18mm end on the kit is also remarkably good, and the stabilizer more than makes up for being one stop slower. I've shot as slow as half-second on the kit at 18mm with great results.

I also tried the 35mm f1.4, and love it for the lack of distortion and the image rendition. But on the other hand I find the AF rather slow and noisy even with the latest firmware. I briefly tried the f2 version, but have yet to come to a conclusion about it. I'm actually not fond of the 50mm full-frame equivalent focal length for walkabout shooting, but for stage photography, it allows me to get shots where 28mm is too wide.

So that leaves probably the 27mm f2.8 and the new 23mm f2 which I have yet to try unlike the 35mm f1,4/2 and 18mm f2.

For portraiture and short telephoto length, I adapt my Nikkor 50mm f1.2 AIS over, Again, the laggy EVF makes manual focusing difficult, but once it's set, I can just switch back to the OVF.

While I don't intend to use the X-Pro 1 as an action camera, I am a stage photographer and I've already used it to shoot 3 gigs casually in the 2 weeks I've owned the camera. It's a paradoxical experience: the OVF focuses too slowly to be really practical, plus parallax errors are a real problem when this close to the subject. EVF focusing speed is much better, but the lag in low light is terrible, so what I end up doing is focus and frame in EVF, hit the AF/AE lock button, then switch back to the OVF and wait for the right moment to snap.

I actually really like the kit and intend to keep it, but I feel I'd benefit from having one good prime as well. Would love to hear your recommendations and thoughts. Thanks in advance.