Jim & Lynn,
The Vortex is my first and only scope...so my experience & exposure to other scopes is limited to occasional views through the scopes other birders are using when I'm in a group.
I do love to digiscope and the Vortex actually works quite well at this. I've made my own adapter and have taken some pretty decent bird photos. I've even been able to use the zoom while digiscoping, sometimes up to full 60X. The image quality suffers due to less light reaching the camera lens but you can still get good photos in good lighting situations.
However, I do get chromatic aberration (CA) with this scope in certain conditions as can be seen in the photo of the bald eagle that is referenced in the link above. ED glass would probably help or eliminate the CA in this scope. I elected not to buy the ED version of the Skyline in order to meet my budget at the time.
I would like the flexibility of using a different single power wide-angle eyepiece for digiscoping. But the Vortex Skyline only has a single zoom eyepiece available.
If I had to choose between zoom and fixed, I'd choose zoom every time. I like the ability to get in close on a bird and see detail. Not just for identification purposes but just to see what the bird is all about. A zoom eyepiece is a great tool for general birding, as you say.
Regarding hiking with this scope. I've done my fair share both carry the scope and a Bogen 055V/701RC2 tripod plus other odds and ends in a very good technical daypack. It's reasonably comfortable and I can hike many miles on flat trails and rolling hill trails. I've also hand carried the scope either over my shoulder or by my side in the manner you've described. It works but is tiring after a while. You need your hands free for difficult trails so packing the scope is a necessity in those situations. I agree that I would probably leave my scope at home on longer or more technical hikes or when backpacking. The alternative, as you point out, is to get a compact scope that is lighter and packs smaller. The Nikon ED50 gets great reviews. I haven't seen much discussion about other compact scopes that are available here in the US. Leopold does make a compact scope that may be worth considering.
In summary, I have been very pleased with my Vortex Skyline 80 and have received many positive comments on its image quality from those that have looked through it after looking through other scopes (Leica, Swaro, Pentax, etc.) being used in groups I was birding with. I recommend it.