I think I'm pretty much searching for the same thing you are, Sumguy.
I'm thinking of getting an iPad Mini. I already have my iPhone 4S.
I want to be reading a book on my iPhone then stop, pick up my Mini and resume reading the same book at the same spot. I don't need to read on my computer (PC). I just want to be able to read the same book on the two different hand held devices.
My ebooks are in epub format and are non-drm. I've gotten them from so many different places but keep them on my PC and currently load them into DropBox and then onto my iPhone for reading.
I don't think I would want to read a book while it was in the "cloud" since it would use up too much data transfer time and wouldn't work if you didn't have a constant wifi connection. What would work for me would be an ebook program that would let you read on one device, then when you switch to the other, have it send a signal of some sort to the other device telling it where you stopped reading the ebook and just start at that point. A wifi connection would hopefully work for just the short time needed to send the information between devices. Either make it automatic (my preference) or on request.
I'm currently reading ebooks on my iPhone with ShuBooks. It has features that work great for me ... my main one of being able to sort ebooks in the order I load them onto the device.... but no way of syncing.
Is there ANY program out there that actually will sync books like you can if you buy them from Amazon and read with a Kindle or Kindle software? It's a super nice feature but I don't buy my books from Amazon.