Having both of these model cameras invites a comparison, although the S5 should be substituted by the current equivalent the SX40. The S5/SX series cameras are much more bulky, mainly it is a bigger lens that justifies that bulk. The substantial handgrip on the S5 conceals the four AA batteries that power it. Some extra features of the S5/SX series apart from the lens are the flash hotshoe, articulating LCD screen and a viewfinder, while the SX40 steps up from the S5 notably in the use of proprietary lithium battery power. The 35x lens on the SX40 gets you to an equivalent of 840 mm (compared to 35 mm film format lenses), although the SX260 is reasonably well ahead of the S5 going out to 500 mm equivalent. It looks like the same 12 MP sensor is present in both the SX260 and the SX40, whereas the S5 gave us 8 MP.
My personal thoughts are there would be few times when more than 500 mm equivalent would be useful (how often do you hear of people having a lens that long for their SLR) so I would be unlikely to buy this camera for that functionality. It is about $150 dearer than the SX260. For me the SX260 wins hands down due to being such a compact camera. While the SX40 is still half the price of an entry level DSLR I am prepared to go up to the extra dosh for the massive improvement in low light performance on the EOS. At the moment the S5 is going to get used less because it only has small advantages over the SX260 and I’d rather go for a low end EOS than another superzoom.