I love the spydiehole, but I think oval works well too. I own a Victorinox One-handed Trekker, and this model has an oval hole. The oval is fine.
I don't normally buy knives with thumbstuds, but I made an exception when I purchased my BMade 530. I can launch the blade on my BMade 530 quicker than any knife I own, and the 530 has teeny tiny thumbstuds. It is a very well designed folder.
Andy