@Rebecca Marks? All reprojections of raster grids/images will cause some change to the original image, in Advanced you will have three interpolation options, Nearest Neighbor, Bilinear and Bicubic available while reprojecting. It depends on factors such scale, coverage area, projections and application of the image that you are using to determine which is best . In terms of image quality from a visual perspective, you shouldn't see any significant visual decrease in image quality. As Natalia Palmer mentioned, it would be worth considering using the MRR format for improved performance. What format are the images currently in?