phil68- there is a noticeable difference in running the RAW images through SNS and converting them to tiff first. I have noticed this difference in both version 1 and version 2. Also, with what I shoot for a living, Architecture, there is a high demand for accurate colors. Sometimes the RAW images don't capture the color temperature accurately, so they must be edited prior to blending or it makes it more difficult after the fact. For example, if the camera warms up the window exposures too much but gets the interior color temperature just right, there is no easy correction for that after it comes out of SNS. Therefore, it's always better for me to make these necessary edits and covert to tiff files prior to running through SNS. On version 2, the RAW files produce a darker image to start with than the exact same images in tiff format. I don't know why, all I know is I have tested this with several sets of images and every time the RAW files produce a darker image.
As for Custom Presets, I do this as well on version 1, but Pro 2 doesn't have this feature yet, so I am always having to start with the default presets. Unless there was an update to Pro 2 that I missed....