Welcome to the SeeMeCNC Community

I've got what at first glance appears to be conflicting problems: gappy bottom, stringy top.
I'm on a rostock max v2, white PETG, 250 extruder/85 bed.

The bottom of the print is ugly. Gappy, rings breaking off, no fun. Almost like my temp is too low, or I'm not extruding enough. The top of my print is much nicer looking, but very hairy. (this picture was from after I yanked off all the cobwebbing.) Almost like my temp is too high, or I'm extruding too much. I'm trying to print http://www.thingiverse.com/thing:1860763, but this isn't the only model that has these issues.
I'm trying out Simplify3D, but also had similar problems on MatterControl.

To me it looks like an extrusion width issue. The reason the top comes out nicely is because it's got next to no flat surfaces for the trace issues to manifest in, while the bottom is showing them off. What is the "whatever the trace/extrusion width setting is in S3D", and did you calibrate it for die shrink/swell by extruding into air and measuring the thickness of that?