I am an immigrant (from Germany). I work in tech (as an investor and previously as an entrepreneur). I support comprehensive immigration reform. That part is pretty simple — it would be hypocritical to argue that something that I have benefitted from tremendously should be less accessible to others. But I have largely chosen to stay out of this particular fight because the arguments on both sides have been too narrow with a lot of needlessly heated rhetoric.
I am quite convinced that the actual impact here will be less than people expect it to be in either direction. The reason is that there are other forces at work that are a lot stronger. Graduate students from places like India and China are returning to their home countries in far greater numbers not only because we have made it harder to stay post 9/11 but also because those countries have rapidly growing domestic economies which offer a lot of opportunity. On the other end of the spectrum of the labor market the far bigger deal is the pressure of technology on wages. I have written about this extensively.
The twin forces of globalization and technology will have far more impact on our economy and society than the changes we are making to immigration law.