has not been my experience with dektol either. i change it when it turns dark brown or starts to get smelly.
Are you talking about long tray life or long life of the stock solution? Most stock solutions keep pretty well. I use Defender 54-D, and it keeps for up to 6 months in a partially filled bottle. Ansco 130 has a good reputation, but it seems to fade after about three months. I suspect D-73 (Dektol) is about as good. Formulary BW-65, which is an Ansco 130 variant, divides the developing agent from the alkali to achieve long life (about four to five months, in my experience).
As a student i don't have the time to develop all the time and i sometimes go without using chemicals for months. I bought the Moersch and love it. My year old bottle is still kickin!
DS-14 is an excellent standard print developer. It is a modern formulation using safer alternatives to hydroquinone, and it performs like classic standard print developers. This developer is recommended for users who use Kodak Dektol, Kodak D-72, AGFA Neutol Plus (discontinued), Ilford Multigrade Developer, and other standard print developers.
DS-14 is suitable for processing in tray, tank and Nova slot processors, and standard developing time is 1.5 to 2 minutes. DS-14 can be replenished by top-off method. Use DS-14 itself, minus potassium bromide, as the replenisher. If colder tone is desired, 0.05g to 0.3g benzotriazole can be
added to DS-14.
DS-15 is suitable for tray processing, and processing time varies with paper stock. The bromide in DS-15 can be increased or decreased for desired result.
I mix Ilford ID-78 for use in my Nova and it seems to last well.