Yes, natural ear dogs can be shown. However, here in Texas I have yet to see one in the show ring. A breeder I know has just had a litter and she has left the puppy she kept with natural ears - so I am looking forward to seeing him in the ring.
From my perspective, since I am wanting to handle my own dogs, I will not have a natural eared dog until they are a lot more prevalent. I am already at a disadvantage being an owner-handler, competing against the professionals, and for a while it is going to be more difficult to win with a natural ear dog. I want to finish my dogs, so I will be cropping for some time to come.
So, I would say, that if you really like natural ears, and you plan to use a professional handler, and the dog is an excellent example of the breed - then yes, go ahead and leave the ears natural. But, otherwise, I would recommend cropping.