Surfer I've tried 2 different types and both did not communicate despite promises by the suppliers to the contrary.
Neuro, I completely understand the rationale behind your comment but I've used 3rd party batteries in all my bodies without a single issue, the issue is that OEM batteries for any camera are completely overpriced, not that non OEM's are cheap, they are probably the right price, if I can get a battery in the UK at £30-40 that works instead of £140-150 for the Canon one then I'll take it. I've seen some listed as low as £13 but I know what the likely outcome is.
I should add I've never had the need to use a 2nd battery on a shoot, LP-E4N has pretty good life.