RX100 ND filter

I am very tempted to get this one over the XZ-2, but the lack of ND filter makes me wait, how necessary would be for this type of device an ND filter for real life pictures (JPG)?, would it difficult to achieve certain shots without it?, like those pics of waterfalls with the long exposure kicking in?

Also, how good is the RX100 with children running around?, I have seen very good samples of night and low light situations, but not really with children running or playing?

Thanks in advance for your comments