Hiya
I agree, have used inkscape and while it does trace line drawings the accuracy isn't brilliant. That's one of the problems with Corel as well, it tends to convert lines to splines so when saved as DXF you have limitations on various things such as scaling etc. Both Corel and Inkscape use the Stentiford Algorithm which is very good but unlike the Zang Suen it tends to place legacy drops on the finished item. ZS is great but has it's own series of issues mostly to do with curves and conversion of straight lines.
Wintop uses best combination of the two but unless your dealing with high accuracy line drawings of one pixel width you will get angular displacement and legacy drops.
For engraving they are fine but for accurate cutting automatic conversion from Raster to Vector isn't really worth beans.
Cad wise I'm stuck with AutoCAD, DeltaCAD and Inkscape are great for cad drawings but most of the stuff I do has to go in industry standard format and my clients all expect AutoCAD files

(Wish it was different, 8K a year on cad packages is a right royal pain )
LaserCUT 5.3 isn't too bad if your trying to scribble something up quick, got some limitations but as it comes with the machine it can be handy (The smooth line feature is very usefull)
Daven, what sort of files are you trying to convert?
best wishes
Dave