Sorry, missed that question first time round.
Tbh I'm not missing the Zed one little bit right now, but then I'm still in WOW-NEW-CAR mode so that's not entirely surprising. What I am surprised about is that I'm not missing top-down driving at all, which is very weird for me coming from 7 years of only owning convertible cars. In all fairness it wouldn't even be right to compare the Zed to the 911 as the costs are just night and day unless buying a brand new Zed and an early 997. That said, you asked...!
The 911 is in every single way better than the Zed. It makes a better noise, it stops better, it goes better, it corners better, it's more comfortable, it's better on fuel, the dealer network is fantastic, and it gets more attention than the Zed did which is a bit surprising. Normally when you get into a car you can kinda work out where you want/need to spend money to get it to where you want it to be, but that's just not the case here. Maybe I'd like more exhaust noise in the future, but for now the flat-six is glorious. If I wanted more power/better handling there's the GT3, but then I'd lose the extra cosseting a vanilla 911 gives you over long distance and also the wonderful PDK box. Outright more power could come from a Turbo, but then you lose the purity of the NA engine. The brakes just don't give up in the same way the brakes on the Zed do so I see no reason at all to touch them, and that's usually the first place I change things.
If I could change just one thing on the 911 it would be to swap the RE050As to MPS2s, but that's just because I have more faith and experience in them: There's nothing at all wrong with the Bridgestones. And I'm still waiting for my flappy paddle wheel to turn up, so I've got that to look forward to as well!