18qt would be very unwieldy to lift and pour, especially if it was fuller and ladles just make a massive mess. I have a 6qt Hamilton Beach that has Warm, Low and High from Kohls.com for $19 for my 5lb HP batches. I find it also harder to pour more precisely. If it were me trying to do large quantities, I'd get the 18qt, but I would put my paste + diluting water into quart canning jars and use the 18qt as a hot water bath to help with dilution. With my 80% olive oil & 20% cocoa butter soap, I did a 2:1 water to paste dilution and that was about right (before scenting) and for only 7oz of paste, i got about 20-21 fl oz of soap which was about 2/3 of the jar. I like using the jars because its very easy to test dilution ratios and plus its dilution right in its sequestering container, all in one.