Got my replacements yesterday and fitted. I'm a lot happier now, and the slight feedback I had always got has also now gone. (Must have been the cracks)
If anything they should provide more stopping power due to larger surface area, I really don't think heat is an issue.
Also I'm producing a detailed report with lots of photos and measurements as today will be the last time I see the old disks as I have to send them back for warranty.
See below for pics