I suppose as loops go 10 miles is quite big. All the best for your grand slam. Next up the100s grand slam??
I hope to get back up to doing the odd 100 now and again. You need to be very well conditioned for them. I'm quite a low mileage runner and I have nearly come to grief on a couple of very long events. Although I'd already had three completions of the Ridgeway Challenge 86, I came a cropper on #4, and my one attempt at the TP100 ended badly at mile 72.