>Some things will be blurry, but no worse than having the compositor do it. Other things will not be blurry, and that's a huge huge benefit.

This is the same trade-off as you would get without it.

The precision isn't an issue, the error build-up is with rounding and it becomes particularly problematic when you have subsurfaces.

As I have said in another sibling comment, if you don't want the compositor to do any scaling, then don't enable scaling in the compositor.