One of the major benefits of the X50 and X51 series is the fact they have both SD and CF slots.
If you have a Camera that uses either SD or CF cards then you can edit and store your images on your Ax, freeing up space for you to take more photos.
I use
Resco Photo viewer to sort, rename, resize, draw on and generally edit my images and then move them to my CF card. I can then wipe the SD card and put it back in my camera.
Using this method you can store thousands of images and always have plenty of room on the card in your Camera.
Also, if you are able to find a copy of
Andyrenamer (the website appears to be down), you can sort and rename batches of images with a few quick taps.