Yep, I was on the fence for a few days because I wanted more snugness like the 9.5 but not as tight as those, and thought the 10 didn't feel quite snug enough. I thought there was a little too much toebox space going on in the 10, almost like a clown shoe. I nearly returned both pairs and was going to start over for another shoe.
But I watched a video last night about good fit for running shoes and it said not to feel for toe space while seated but do it standing it up because the foot will move further forward into the shoe. Once I did that, the toespace felt just perfect, just under a thumb's width.
Now I'm completely decided and am very happy with the 10 and have returned the 9.5 for a £60 refund. They're super comfortable, let my feet breathe, no constriction at all and very light. At first my feet rolled inwards and I thought maybe I had over pronation. But it seems it was just about getting used to the curve of the midsole. I've never worn shoes with a curve like this so I guess my balance had to adjust to it.