I agree with the others.
The main point about stopping HRT later is that you will be post-menopausal. Therefore there are no longer the hormonal fluctuations (of oestrogen and progesterone) that initially cause the most distress during the per-menopausal years. Progesterone and oestrogen remain at the levels they will stay (approximately) for the rest of your life (some oestrogen is produced by fat cells so weight changes will cause a little variation).
And yes you're right Polly - oestrogen deficiency is for ever and some symptoms/conditions will only become apparent in later post-menopause - such as VA, bladder problems, osteoporosis, heart problems etc - but it is unlikely that the onset of some of these will be attributed to oestrogen deficiency, even if this is a contributing factor.
As others have said some of us are more sensitive to changes (a reduction) in oestrogen at whatever level. For this reason alone and thinking long term I am glad I started off at a medium level of oestrogen ( even though I would prefer it to have been higher) because many women seem to react to any reduction rather than a particular level in itself.
There is a research paper which showed that for those women who are sensitive and whose flushes will return - tapering off slowly made no difference to the outcome (of flushes or not), although obviously the return was not as rapid (ie not as dramatic as Stellajane says) with the taperers. The study was not long term though - only about 9 months I think (from memory).
Anyway even if symptoms such as flushes do return at say 65 if one stops then - well depending on when menopause and symtpoms started - let's say 52 - you will have had 13 years free of symptoms, as well as 13 years of added protection against long term conditions! You can't take that away!! let no doctor try to persuade you otherwise.
I am quite prepared to experience hot flushes again when I stop (not sure when that will be - as long as I can tolerate a bleed and if my health does not make it impossible or inadvisable) - but at least I won't be working (I am now).
Most women now have to work until 66 or even 67 before getting their pension so long term HRT users and bleeders will become more widespread in years to come.
Hurdity x