Miyu!Shirou would likely wish Fate!Shirou the best, hoping that this Shirou doesn't keep making mistake after mistake and lose everything in the end. Fate!Shirou wouldn't agree with becoming the 'villain' but he would agree with saving Miyu in accordance to the "Save Everyone" principal.
Saber would probably sacrifice Miyu in contrast. Although Fate!Shirou converted to Archer's way of thinking would behave differently and could either go HF or UBW (try anyway, at least you tried thinking) with the decision.
EMIYA would sort of understand where Miyu!Shirou was coming from, but would ultimately be the Seigi No Mikata and give Miyu up if he was in Miyu!Shirou's shoes. But in his capacity as a Counter Guardian he would probably be protecting Miyu instead due to plot reasons. Besides, no one seriously trusts the Ainsworth for the whole 'save the world' thing being altruistic, not Gaia nor Alaya. Curious thing to note: He will never attack Illya in any timeline, even if he could have ended the Grail War easily and the later complications.
In the end, Miyu!Shirou wouldn't hold anything against most other versions of himself since he's "been there" and already made his decision.
Oh, I wasn't necessarily saying Miyu!Shirou would be antagonistic. Just more that they would fundamentally be unable to truly see eye to eye, at least in the beginning of the Grail War.