"Alt-az mounts that put the scope above the pivot point struggle when the scope is pointed toward the zenith".... "Twilight I's + or Portas might be better choices"
...Excellent point.... that rules the AZ3 out.... probably more suited to looking at ships on the horizon :-)
Zenith access is a key requirement of mine, since the richest regions of the milky way pass directly overhead at my latitude (Scorpius, Puppis, etc)
I'd still be a little concerned about access to the Zenith with the Twilight I's. However, with their offset design, the Vixen Portas look like a great solution!!! Thanks heaps!
The AZ3 might be ok If you're not using heavy Wide Field eyepieces (31T5, 20mm 100's, Etc).
..... as a matter of fact, I'd be using heavy 2" eyepieces, eg: 35mm Panoptic.
Consider a vixen polaris mount with an adm saddle. I dont yet have the saddle (I do have one for my super polaris mount) but I can tell you that this mount gives my twilight i a run for its money and its far lighter andthe tripod is more ridgid.
.... the Vixen heads are quite expensive... If I went for an EQ, an EQ3/5 would be more cost effective way to go, though not sure how an EQ5 compares to the Vixen AP head?