Soft Fuse vs. Full Fuse
To me a soft fuse is in-between a full fuse and tack fuse. You still have some texture or definition of the individual design components but not as much as a tack fuse.
Why do you want to grind away part of the opaque? Are you aware that grinding can cause a haze look, esp. if it is a dark color, or blues?
If I had to do this design, I would probably do a soft fuse, remove the part that you want to remove, cleaning immediately and completely, spray with Super Spray,, then full fuse.