I started out with the 10psi pulley and am now running the 12. While I would like more of course, I'm leery about pushing the stock internals any further.
Keep in mind, you may run into fuel supply issues even with the 12, unless you do some upgrading. And you should get it retuned for the 12 because more air will be flowing and more fuel will be needed.
For the fuel supply, do datalogging on your FPDC (fuel pump duty cycle) and see how close to 100% you get at WOT/top rpms. With the stock wiring/setup, I was around 95% with the 10 psi pulley. I did a wiring upgrade and got it down to like 85%, then with the 12 psi pulley, I'm back at near 95% at peak rpms/peak boost. No way would I have been able to deliver enough fuel for the 12 pulley with the stock wiring. Of course if you have a BAP then you're probably already set.
I also saw more crankcase blow-by pressure, so make sure you have adequate crankcase ventillation to allow the pressure to escape. I use at least one breather and sometimes two now.
There's always something else to be aware of with more boost

.