I've had 4 doubles - Spinlock XAS for 10 years and have had just one small part fail on just 1 of the 8 clutches. It is a small locking mechanism that activates when the clutch is fully closed (I don't know what the part is called). It appears that it is replaceable, but I've had no releases, despite the missing part.
They've been exposed to UV the entire 10 years. Other than fading, there has been no loss of function. I've experienced no slippage or excessive wear on lines from 3/8" to 7/16".
I'll be happy to replace them in kind. The XAS is priced right for our boat. On a larger boat, I'd consider an upgrade in working load - like the XTS. I like that they have greater working load & are more stylish than garhauer. And the price is right in SBO store. If I were you, I think I'd select the XTS, particularly with the experience you've had.