Hi Julia, I have one of the Delkin twin chargers and can confirm they are indeed an excellent investment. I only use LP-E6 batteries for my 70D and 5D3 but to be able to charge two at the same time is great. I use my batteries in pairs as I have grips on both bodies so it suits me perfectly. I do have the single chargers from the two bodies but I can't remember the last time I used them. Unfortunately the 3 cameras you've got all have different batteries but the plates aren't too expensive for a pair and you can put two different plates on at the same time.