I've had a dual-flush in our main bathroom for about 6 years now. Mechanism went wonky once, but it was an easy fix (thank you, YouTube tutorials...)....

Haha, sketchy plumbing sounds familiar—my old house had pipes that looked like they'd seen both world wars. Have you checked out low-flow fixtures yet...

I went the thermostatic valve route too after messing around with fill valves and pressure tweaks. Honestly, it was night and day—no more shower anxie...

I usually do mine every year or two...mostly because I'm paranoid about efficiency and hate surprise repair bills. Plus, keeping it tuned up helps kee...