You might find the Better View Desired website very interesting. It lists the Pentax
80ED to be the reference standard for 70-80mm scopes
, mostly because of the eyepiece that it normally comes with.
IMO one scope does not stand higher than the other, so I would be very happy with either. If I were to purchase one today, it would be the one that I could find at the lower price. One thing to consider is that the Pentax
can use regular 1.25" telescopic eyepieces, and there are a great many good ones to choose from, in both fixed and zoom focal lengths.
That being said, I'm not sure if even an 80mm ED spotter of any brand will do well at 5300 yards. You should probably be looking at a TeleVue
85 or similar, along with a backpack big enough to carry it and the tripod
you will also need......