I would definitely test. However, I can also tell you that when I did a search on eyetracking studies for a similar question we had at my work I found that the eyes stops at the form. So if you have content you want people to read before they get to your form, eyetracking seems to indicate right side placement. In addition, make sure the spider hits text before your form. This can be done in a number of ways, but don't feed the spider a form first. Our testing on this has shown it definitely will affect organic rankings (someone removed text from above the form on two sites of ours and both dropped dramatically in the rankings.)

Good luck!!