Okay, thoughts:

How was buying an entirely new instance of the exact same bicycle ever a reasonable means of upgrading your groupset?

If you're so die-hard Shimano that you're willing to buy an entirely new bike for an incremental improvement within the same shifting family, why would SRAM ever factor into your options, even at a reduced price?

Why are you worried about long-term reliability if you swap groups every three years?

Could you simply admit you just want more shiny stuff, and you're seeking strangers' lukewarm rationalizations to repeat to your wife?