Nill rosewood are beautiful and fit my hands better than all the rest. I don't have Jordan troopers but have tried them and I prefer the Nill replacement closed back grip. Just as an obervation (with no basis in fact), it seems like the Nills are CNC built as they feel identical from grip to grip, whereas it seems the Herretts have a more handmade "one at a time" crude look to them. Herretts seems more like old world craftsmanship and Nill feel more like high tech/new world manufacturing. Maybe it's just that the Jordan style is very plain to me and that is why they do not appeal aestetically. I do not have any experience with the fit of Herretts, but I can say that the Nills fit so tight, you almost have to squeeze them on and the seam is barely visible. They are extremely well made.
Only drawback is they come from Germany, so expect to wait a month to get them!!!
IC