All single shot backs have color moire, even the 50MP backs. This is because any single shot back captures only 25% of the red and blue color information, and 50% of the green color information. For example, a 50MP single shot back can only capture 12.5MP worth of information in either the red or blue channels, and the missing 75% of the color information in these channels must be estimated post-capture. No estimation can recover this missing information perfectly, and so color artifacts will ALWAYS be possible. On the other hand, a 22MP 4-shot image will contain 22MP of captured color information for each of the red and blue channels (and green of course), which is almost double the amount of red and blue color information that is captured by a single shot 50MP back.
A 16-shot back like the Sinar 54H delivers even more resolution and color information (ie, 88MP of captured color in each of the red, blue and green channels). Even adding 4-shot capability to a 50MP back (ie, 50MP of captured color information each color channel) will still only deliver about 57% of the resolution and color information as compared to the 16-shot image. To my knowledge, the 39MP and higher MP backs will not be capable of 16-shot.