Hi Ed,
I'm using an AZ-EQ5 pier version with an Explore Scientific AR127 5" doublet in alt/az mode and love it. My scope comes in around the same weight as yours. Your scope is a little longer at f/7.5 so I guess that could make for slightly more difficulty, but there's not that much in it. I've never noticed any problems at all with the mount's ability to carry this scope. I will note that my mount came with just under 1mm play in the az worm (alt was sweet though). To their credit, Skywatcher (Tasco) quickly tuned the mount for me after I approached them about it. I'm expecting the mount back tomorrow - so that took just over a week to tune it up for me. No problems with their after sales support.
I guess at the end of the day it might get down to how fussy you are too. I'm visual only, and had the same issue with the AZ-EQ6 - it didn't cost that much more, but the weight was killing the deal. I have reasons for requiring lighter gear than I used to use
No more lugging a 15" Obsession around sadly. So it all gets down to compromise at the end of the day I guess. For my use, the AZ-EQ5 with an ES AR127 is an awesome pairing and I just love it.
I did look into the iOptron mounts when I was researching the AZ-EQ5 / 6 but I kept finding bad feedback about them. I spoke to an iOptron dealer who I trust as well, and we both agreed that for my requirements, the AZ-EQ5 was the superior mount.
In retrospect, given the after sales support that I received from Skywatcher - choosing the AZ-EQ5 for me was a solid move.
Dean