If so, one of the observations I've always made is that standard MGIV just doesn't have the beautiful deep maximum black / D max that MGFB Warmtone naturally (untoned) has. This makes a significant difference in the appearance of the total contrast and image depth.
Selenium toning, although very effective in boosting that maximum black with standard MGIV too, just doesn't solve the whole problem though compared to the "natural" deep blacks without selenium on MGFB Warmtone. I somehow feel selenium toning, although effective in boosting the maximum black, also changes / flattens out the contrast curve near the low values / shadow / black end of the paper curve. This may lead to apparently, or visibly, less contrast in shadows compared to a "natural" untoned deep black like the one of MGFB Warmtone, where the contrast curve may be more straight line in the shadows.
What are your thoughts on this?