Fixes to the OS are pretty safe. New versions of the OS are another story. They used to be better before Steve Jobs passed away but it appears their quality control has slipped a little. I made the mistake of accepting an upgrade to my iPhone and I still can't send email or files by texting.
I move files between systems all the time because I run a tower and couple of laptops. The tower is my "standard" system and the laptops slave to it. For small stuff, WIFI works well. If I have to move massive amounts of data, I cable up the internet and move stuff that way.