I use both Solidwork and Alibre almost daily. I use Alibre Expert and Alibre
Cam 2.0 (vm6) for tool pathing with both native Alibre parts and directly imported SW parts. On many parts I have modeled them in both just to see how they turn out. While Solidworks has a much much larger bag of tools, I find Alibre much faster and less fatiguing. There are some things Alibre simply can't do, but what it does, it does well. Transitioning between them has not been a problem.
In my experience, if I can't model it in Alibre, then I probably can't mill it anyways, and, if you need more advanced
CAD functionality, then you already know what you need and will be able to justify the expense.
I would recommend Alibre standard till you get familiar with parametric modeling. Then wait for one of Alibre's frequent sales on upgrades and get the pro version.