I have a DB....the 1.5 I believe. I load the pre-heated scuttle (pre-heated with hot water) with boiling water and usually use a soap, cream, glycerin mixture. I get good hot lather for all passes. HOT!
Is the lather weak? Not that I have noticed. Compares favorably to my best mixes without the boiling scuttle water. Might have to mix the lather with a touch more water to prevent some drying but it really works for me. Experiment.