So I have had a sd450 for a loong time. I am ready to get a new camera and I was looking to spend around $300. I really want another camera that uses SD cards since that is what I have a bunch of. I like high iso or at least decent for a compact. I also like li-ion batteries but not 100% tied to them. I was looking into the SD750, SD850, SD870 but I don't really know the difference between them or if it would be worth it to spend the extra money for the SD950. MP over 6 is not really too important to me. I also know very little about the A line but they look pretty cool. Also if anyone has any other suggestions for cameras not canons that would fit what I am looking for I am open ears.