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If you have enough money to put that many rounds through either one, you could easily buy a decent 1911 or three Glocks or so (~$.15/round on the very cheap end, 10,000 rds comes to $1500) over that time period.
But to your question, I believe that longevity is not necessarily predicated on caliber as much as it is on maintenance and upkeep, at least with modern reputable guns.
As far as pressure etc., each caliber gun will be built according to required pressure specs, so unless you are shooting 10,000 rds of +p+ in 9 as opposed to standard 230gr ball .45, the difference in longevity will really be imperceptible. My opinion at least.