How difficult to swap out gauges for smartcraft?
 

I wanted to redo all my gauges but my mechanic said going all digital is cheaper and better. Another buddy told me that I couldn't go digital since my motors are 2000 MY.

you would need to double check the engines but from what i have seen online about them:

Can I use SmartCraft on my older engine?

The SmartCraft line of products are applicable to all Mercury/Mariner OptiMax outboard engines starting with Model 2000, and all MerCruiser 8.1 liter engines for Model Year 2001. The SmartCraft line of products will not retrofit to any previous Mercury/Mariner or MerCruiser engines.