18:1 Compression Ratio

[93GMCSierra]

I think I would, because getting a longer glow cycle is not a problem, and running higher boost will pack that combustion chamber so the compression is there and you get cleaner burn and lower egt with more air.
And of course the option for more power if and when it will be needed.

[More Power]

The gray areas of vehicle use make it hard to know what to do. One gray area would be a 6.5TD family rig that tows only occasionally, but is used as a people mover most of the time. I'd probably lean more toward a fuel economy build for that vehicle - small port precups & factory CR. Plus I'd add a few other items that improve efficiency - like gear drive timing set, intake/exhaust mods, etc.

On the other hand, if the vehicle will be used to tow heavy more than occasionally, I'd build in some durability and power - like 18:1s and hi-cap cooling, along with turbo & fueling mods.

A little trivia.... The Duramax began with 18:1 CR in 2001, and now is at 16.8:1 CR.

Jim