Given a choice, I'd tend toward the Prostaff-5s. I understand the niceness of the small size and the excellent
sharpness on the ED50s, but they max out at a lower power, no doubt for light purposes and not resolution
troubles, and (since you granted a pardon on size) the 82mm light grab makes a big difference at higher power.
Bear in mind, I'm on a 70mm/f-10 astro kick right now, running 70x for eagles.
Extremely light, but not suitable for long-distance travel (focuser is too cheap).
I really need the long barrel but with nice multicoatings instead of single.
My spotter is a 60mm 3-element-objective Swift 839, at 12 inches, 20x and 40x. It's 3 lbs, though.
Similar niche, just not as extremely compact as the ED50, and not as comfortable pushed to 70x as the astro.
If you want the lower power to have a really large fov, the ED50 is still awesome. And---it's very small.