The trick with any drum system is getting the air inside closer to ideal process temp, and not just the outside of the drum via a water bath. The better the drum is mfg, the better it will insulate to keep temps inside the drum consistent longer. For instance, my best drums are made of expensive noryl plastic - an excellent insulator - followed by thick ABS, then thin ABS as the least insulating. But that very virtue becomes a liabilty if you're relying only on external temp control. If you are relying on outside temp, thin stainless steel is preferable for exactly the opposite reason: fast temp transfer. Nobody is going to pay for grade 316 large stainless drums necessary for typical paper sizes, or want to deal with the extra weight. Therefore the simplest solution is just to pre-temper the inside of the drum with a wetting step. I also find this absolutely necessary to get rapid even spread of the developer on large color prints to avoid streak or drip marks.
In fact, during the fill phase - the first 10 seconds of the development cycle, I speed up the drum rotation, then slow it back down for the
duration of the cycle. And with film, whether trays, hand-inversion drums, or automated drums, I have standardized on a prewet with
every film & developer combination I can think of; and given my consistent results, see no reason to change that habit. With tray development of sheet film it's vital in my opinion. When sheets first enter a fluid they tend to stick together, and that's the last thing you want when development starts.
