I just had my dealer order one. It took less than a week to get it.
I like the 15/50 combo. I had 15/47, but with my weight & headwinds it was too tall, no torque.
So far (a couple of weeks) 15/50 is working great. Usable first gear, and still has a little torque above 55MPH. It doesn't drop below 60 uphill into the wind anymore.