When I opened the thread I was expecting to see some shampoo bars with beautiful sunset colors
The shampoo bars that are generally considered pourable such as the ones in Swiftcraftymonkeys website/blog are still not really pourable they are more "glopped" (for lack of a better word) into the mold after the ingredients are melted and blended. These bars tend to have a number of different surfactants such as SCI/SLSa/Cocoamidopropylbetaine and you can also add butters and conditioners. These bars can be pH balanced depending on the surfactants selected.
I have never had any trouble with these types of bars disintegrating.
I have never made a pressed type of bar so I can't really comment on them but some of the recipes out there don't seem to be much more that SLS or SCS pressed into a shape which is not what I would consider mild.
Hope this helps.