Only hackers use anything other than Proe or SDRC.
I have made a good living fixing the mistakes made by peolpe trying to be cheep the first time by using one of the lower end CAD packages to do products. You get what you pay for!!! The reason ProE is difficult to use is because of is accuracy. It will not allow you to make the hacker mistakes you can get away with in the cheap, easy to learn, programs. They allow mistakes in the data that will come back to haunt you when you start cutting production tooling form it.
"Do it right the 1st time" is my advice to anyone trying to develope a new product. Or you will end up paying for it twice.
Actually having sold, supported and implemented (Level II CEP) Pro/ENGINEER for the past 16 years - back to Rev 4 - I can say honestly that there are some packages that are approaching the performance of Pro/E in basic modelling. These are the ones I listed above. For general purpose prismatic parts they work pretty well at a significant savings in learning curve and cost. When expanding from prismatic topology into lofted surfaces or using higher end functionality such as cable routing, harness layout sheetmetal, integrated 5 or 6 axis mfg., mold design, etc., etc... the Pro/ENGINEER package offers a wider integration. Only CATIA can compete across the board with Pro/E's total functionality. However, only a very few shops need that breadth of functionality. The midrange packages such as Solidworks and Inventor do a fine job in meeting the needs of these users.
Evaluate, evaluate, evaluate.