I have the ECO, with an EF nib. It's not scratchy at all -- it's almost ghost like if you want to make very fine lines. At max pressure it's about the same size as a roller gel.
It's the only fountain pen I have (I have an ancient set of adjustable dipping pens from my great grandpa's engineering toolkit, not sure if that counts), so this isn't an expert opinion or anything.
I mostly write in a moleskine, which isn't supposed to be great for fountain pens but works fine for me.
Edit: just to say, I got the plunger stuck at the bottom, and was about to toss it when I found out that there's tutorials on how to completely disassemble and reassemble the ECO, and forums where people talk about the exact problem I had. It's super easy to maintain. Reminds me a bit of owning a VW -- you think "I can't possibly fix this," and then you start tinkering and it's fixed before dinner. Except the pen takes about 5 minutes.