Great post and an important distinction made between psychogenic and organic causes of RE. A sudden onset of RE late inlife is usually related to a physical cause. Although, there is something called "Widower's Retarded Ejaculation" which occurs when a long married widower attempts sex with a new partner after the death of a spouse. Despite the advanced age of the men in these cases, the Re is usually always has a psychological root cause- guilt, performance anxiety etc. In older men, low testosterone levels, heart and central nervous system diseases should all be considered. Sadly, in older married couples sexual boredom can also cause RE.
As you said the biggie on the non psychological side are the Tricyclic and SSRI antidepressants. This have the effect of putting ten condoms on your penis before intercourse. Interestingly, the numbness and loss of libido caused by these drugs is very much the same as is caused by the anxiety/low arousal levels in psychogeniclly caused RE.
Adding Wellbutrin to the ant depressant as a combination therapy has helped many men who need to take the Tricyclic or SSRI medications but proper dosage levels take awhile to be found.
The Holy Grail for the big Pharmas is to discover a drug which significantly boots arousal levels-- enough to overcome both the psychological blocks to reaching orgasm AND to override the effects of the medications that have Retarded Ejaculation as a side effect.
For non depressed men, Wellbutrin and Viagra work in some cases. But so far, with the exception of the work with Surrogates done by Bernie Apfelbaum, Sex Therapy has shown little promise in treating RE, there is still much research to be done.