Slappies were really a thing first time around before eggs/ footballs. In saying that, I do think eggs are good for slappies. Probably in my head, of course. I like to have a narrower stance for slappies. Front foot behind front bolts and I think the middle width of eggs helps with this. I also like the tapered nose for slappy Ks. But as I've said before, slappies are great because they can really be done on any set up...
..its just a feeling, man..