I feel your pain, I've been in the same boat for years. I'm suspicious of non-natural stuff too, although SSRI's (anti-depressants) DO work, at least they make me last longer. But then they also make me wanna have sex less too cos they shut my libido right down.
I see the ingredient list for Deferol contains folic acid, I know there are some studies about a possible link to pre-E and folate, check it out maybe if you want to do some more research?
(I can't post the link here but the study title is: "A new potential risk factor in patients with erectile dysfunction and premature ejaculation: folate deficiency" - search for it and you'll find it)
If you decide to try it I'd be interested to hear how it goes.