So I had my first "no moon" session with my 15x70s last night. Sky was very transparent.
I spent an hour or so early in the afternoon really trying to dial in the balance on my Peterson mount. I think I've got it about as good as I am going to get it. With my 10x50s, the Peterson mount is essentially perfection. With the 15x70s, I'm not quite there yet, especially in the "pitch" axis. With the 10x50s, I didn't have to use any of the friction knobs, but with the 15x70s, I have to use all three, with two of them -- pitch and roll -- tightened significantly.
I think the problem is that the place in which the tripod threads is not the balance point of the binoculars. It's like a newtonian reflector, with all of the finderscopes and stuff on top of the tube, you can't get it perfectly balanced in altitude.
Still, I certainly am willing to give up a little bit of fluidity in order to keep the weight of the entire thing down. It is very important to me that I can take this mount + binoculars from my garage to my driveway in one trip.
I did some variable stars in Lepus and Orion before the Moon rose. The sharpness in the center of the field is really a joy. I was not expecting them to be sharper than my Pentax 10x50s. I'm really enjoying the extra magnitude grasp. It's actually throwing me off a little....A 7th magnitude star now looks like a 6th magnitude star! A good problem to have.
I love the center-focus. My contacts correct my vision very well, so I really just set the right-diopter to zero and then use the center knob. I find this much, much more pleasant than individual-focus. The center-focus, in my mind, offsets any improvement in optical quality the Ultras would have given me.
I may....may think about adding a reddot finder to the setup. It's not necessary, but the smaller field did make me question whether I had pointed at the right star a few times, for example, in the western "foot" of Gemini.
All in all, there is no free lunch in astronomy. To gain something one must always give up something. So I got a slightly heavier setup, lost sone fluidity, lost a bit of field of view, but gained a sharper image and the capability to more easily detect some of my variables.
(Also, the Double Cluster in Perseus.....diamonds on velvet!)