I have tried reading the same book on both a Kobo and a Kindle, switching between chapters. The reading experience was essentially identical; the Kobo has more display control but that's entirely a matter of personal taste. I currently read on one or the other depending on where the content was purchased.
I like the idea of syncing but the reality is I am not going to read on a Blackberry Torch; I'll surf news sites there if I have spare time. And I dislike long form reading on a computer with the exception of lengthier newspaper articles.
So for me, syncing is most helpful as a back up. I happen to have two Kindles and two Kobos so if the battery dies on one, I can pick up where I left on by firing up the back up device.
