I don't know what they mean by 'ground flat', but if you're thinking 'quiet', these aren't it. Finger squeak, pick noise etc. these have it all.
If you want that Martin sound, and only play in the first position, maybe these will do. They don't for me.
And I wish D'Addario had a better Customer Service Dept.
The treated strings can be good, but they're more expensive.
These "flat tops" are what I keep coming back to. Great warm sound for weeks.
Regardless, I'll probably wind up with "13's" before it's over. With "13's" there's just more wire wigglin' and and the sound should be just that much stronger.
But D'Addario is referring to the flat surface of these *strings* -- they're polished down _flat_ - to rid them of finger-squeaks. And these strings are AWESOME. For acoustic archtop jazz guitars, there is nothing even remotely as good. Loud, smooth, warm, and so evenly-balanced from bass to treble, you'll want to play all night. Super-clear overtones make for ease of tuning (if that makes sense! The "ring" they emit, whether played open or "chimed" at the 12th or 5th or 7th frets, is crystal clear, and if you tune away "beats" - you'll love these.)
Great strings. Try 'em. And, Mr. D'Addario: consider changing the name! I'd hate to see these go off the market because too many people misunderstood their purpose. They're great for "flat top" guitars - but also great for non-flat-top guitars! How about "Acoustic Smoothies?" Okay, not that, but, imho, it's better than "Flat Tops." : ) Of course, if they're selling great and have a secure future, don't change anything! Ha.