John,surely they are slightly different animals if low light or out and out speed is needed in the images you try for ,like bolting hares fast bifs etc then the 1D would be the choice to pick up,if you are working with slower frame rates or focal length challened for nature togging then surly the 5 series has the edge because of the pixel count. I haven't used either but have dreamed alot ,LMAO I feel it is the type of images that you usually go for that will be the biggest factor in making this choice. So analysing what you actually go out for might be the biggest factor governing your choice,they are tools for a job it's working out which is the best tool for what you do. Cool choice to have mate all the luck,which ever you go for,
Me I'd have the 1D: i'm so hampered by light levels and wanting to shoot late john ,so many of our wildlife subjects here are busy at dawn and dusk so often the light here in blighty is low especially through the winter,being able to really push iso and still get great IQ would be a huge thing personally,i'd imagine this situation prevades many folks thoughts here.that shoot nature
Can't wait to see the images john all the luck as always a beginners take ,no substance ,but much dreaming
Stu