I agree with Jethro10 about the syncing thing. I run Ubuntu myself but have never "synched" anything with it. It's important to keep in mind there is no equivalent of iTunes for Android. One good thing with Linux in particular is that you have direct access to the external and internal sd cards of the phone without the need for downloading drivers. Just plug it in and you're ready to go.
If you're referring to "flashing" as in installing new ROM you don't really need anything other than access to the internal sdcard, BUT there is this program called Odin that can come in handy when you're phone gets soft bricked, but sadly it only works in Windows. But that's what vmware is for, right.