Solidworks or Pro-E can do just about anything you want, add some of the FEA software and you can reliably test stuff too. Both do require a bit of learning, but I can tell you that it comes quick just playing with it. I have never had a class in Solidworks (I have had a Pro-Engineer class), but I have done all my school work on it in the past couple years. The cost of the software (especially if you get an FEA suite) is the drawback. Really there are very few shops that would even use something of the sort. Most just design-build, changing plans as they go to fit the rig... seems to work just fine. If you were planning on mass-producing something, than a solid modeling program could help you cut some costs, save some time, etc...