I totally agree with royblumenthal. I use a vector program when I want to draw lines and shapes graphically.....but ArtRage when I want to paint with artistic expression and not be encumbered by the "preciseness" required by vector drawing. It's like the difference between drafting a house plan and painting a house portrait. IMHO perfect linework doesn't belong in an oil painting that, in most cases, is impressionistic.
That's what's so great about ArtRage. It's uncomplicated and fast and allows you to be creative without having to stop to think about which tool to use next.
Having said all that, I remember seeing a post where someone suggested creating a grid image and using that as a tracing layer when straight guidelines are needed....such as getting the horizon level for a seascape!
A grid overlay might be a good tool to have built in! (or is there one and I missed it?)
"The one common element that I have discovered when studying master painters is that they were all 'students'." ~ Stephen Quiller