IMHO, warmtone papers are much more interesting in selenium than neutral ones.
I don't necessarily agree with this. The effect of toners in general is stronger on warmtone papers, and certainly, warmtone papers toned in selenium tend towards a warm chocolate brown as you mention. This can be very pleasing, and indeed, I like it, too. However, I personally find the response of neutral papers to selenium just as worthwhile. For one thing, it helps to get rid of the green cast I personally don't really like. And with (much) stronger toning, the eggplant hues that selenium gives on neutral papers I personally find very beautiful. But it's all much more subtle than the strong response you get with a warmtone paper.