I keep wanting to play with markers, but .... the thing I hated as a kid was the l.ines that would show up when you went over previously colored areas - I HATE that.
Do the art markers REALLY not do that? I just have a hard time believing it enough to shell out any cash for a set. LOL.
My experience with the Copics, certainly, (and I think that the other brands are the same), is that this still happens -- but, you can come up with techniques to overcome the problem.
I'd be interested to hear other people comment regarding their experiences with this.
What I've found is that, in the first place, it depends on the type of paper used. I use a coated heavyweight paper, and yes, when I'm first laying down color, I can see the issue you're talking about. My workaround has been that I obliterate the lines by saturating the area with that color.
What this also means, for me, is that I have developed my style to create a lot of smaller areas that can be more easily filled and saturated so as to avoid areas of too-inconsistent color. Obviously, once you start doing shading in those areas, that breaks things up too. I simply never do a very-large area of a single color with the markers; that's what Photoshop is for! (I use that pretty often for a cloudless sky, for example.) But any other area of any piece I'm coloring is usually being colored in such a way that it's a lot of little areas of color variation (shading and so forth), so slight inconsistencies in color coverage don't matter.
Another factor is that I believe some of the art-markers offer "blender" options. Maybe someone else here can speak to those; I haven't really used the technique. I get the impression from others that it only works on certain types of paper.
And refillable? Really? ::perkperkperk::
Well, the Copics are. I don't know about any of the other brands, although I'm pretty sure that the Prismacolors aren't. (I recall that from when I was comparison shopping before making the big investment.)