Both of those are great machetes - I own those and a bunch of others.

What I like to do is file the edge close to the profile I want, use a stone to get a nice edge and the touch it up with a carbide sharpener in the field. The edge gets dull quickly on even the best machetes.

I have also cut grass (on a 30 deg slope!) with a long handle machete with a bent blade called a "brush cutlass". It works just as well as the grass blades like they had in "Cool Hand Luke" and probably better on the thicker grass.

If you want a workout, swinging any kind of machete will do it!