45x is plenty, Paul. Or that's my feeling (and I have a Swaro 80mm with 20 - 60x). I don't use the 60x end of the zoom range much at all, not for just looking and enjoying, and certainly not for photography (which is my main love). I do use the full 60X for ID purposes though, particularly with largeish birds a very long way away (ducks and cormorants, for example). But all that does is (maybe) give me an extra tick for the day, or confirm a guessed-at identification. Even with the Swarovski ATS80HD's magnificent optics (and even more impressive price tag) and Australia's wonderful daylight, 60x is pushing the limits further than you can really go and still get good quality views.
In fact, if Swarovski made, say, a 15-45 E/P for the ATS80 instead of a 20-60, I'd buy one like a shot. I would use the 15x, and if it had a 10x I'd use that too, especially for photography.
But the 60x, that's more about show than go. People ask to look at my scope and I show them the 60x zoom and they say "wow!" But people who already know a little about optics - the peope in the local birding club, for example, who all have binoculars already and sometimes have their own scopes, or people who are familiar with telescopic rifle sights - these people tend not to be so impressed by the 60x end of things: the thing that really knocks their socks off is the clarity and brightness around 20-30x.
If you can stretch to a Zeiss 65mm with 15-45x (or even with a fixed E/P), that would be excellent. I've never used a Zeiss scope, but people I respect have written about them and say that they are in the same class as Swarovski and Leica - i.e., superb. OK, it's 65mm not 80, but even sight unseen I'd have a 65mm Zeiss scope over a 80mm-class scope from a lesser maker any day.
I don't often get to try other scopes, but the other day I swapped with a Kowa owner for a few minutes. The difference was amazing! The Kowa, a 65mm one I think, was sharp enough in the centre of the field of view, but the FOV seemed tiny and really only of 1st rate quality near the centre. Overall, although the magnification was about the same, the image seemed much smaller and more vague, and you have to hold your head just so to get any picture at all. After being spoiled with the Swaro, it was quite a let down.
(Then I had a look through her Swarovski binoculars and the tables were turned. My bins are such cruddy little ones that I don't even bother getting them out of the car: I can do nearly as well with the naked eye. There is a lesson there too: those cheap Gerber 20 x 10 bins still cost over $100, and the money was completely wasted. That's 1/25th of a pair of top-class Leica/Zeiss/Swarovski bins that will last a lifetime. If I hadn't spent that $100, I'd be that much closer to the real thing.)
But back to scopes. Let me put it this way. With the Sarovski at 60x or the Kowa at any zoom level, you can see the bird. With the Swarovski at 20x or 30x, you are right there with the bird, you can almost forget that you are looking through an artificial visual aid and just enjoy.
Spend the money. You won't regret it.