I run an IP5200 and until recently would never, ever had considered compatibles but I'm now on my second set of 'Think' cartridges and I'm completely sold having seen no difference between these and Canon - apart from the price!!!
I have an ip4600 & (apart from the first time) have always used compatibles purchased from eBay with no problems. Each time the cartridges have arrived individually boxed + sealed & are less than half the price of Choice/Think cartridges. G