Hubble presently resolves Eris into a ~1 pixel wide image (Eris is 2,326 km across and Hubble resolves a spot 1,875 km wide at Eris’s distance), so an Aragoscope would image Eris to a ~1,000 pixel image – thus ~2 km/pixel resolution. Unlike Pluto, there’s no “New Horizons” winging its way to image Eris.
We could scan the moons of Jupiter at better than Galileo resolution. At just 4 AU, when closest to Earth, we’d see Europa to the ~0.1 km/pixel level. What does that mean? This is Europa at 1 miles (1.6 km) per pixel…
The moons of Uranus and Neptune would be imaged to the ~same level as the above image of Europa. What’s more they can be studied at leisure, rather than the frantic scramble of a high speed flyby.
Mars can be monitored at the 10 metre/pixel level. Not as good as the rovers on the ground, but a decent bird’s-eye view.
Finally the mysterious possible planets out beyond Neptune, at ~200 to ~250 AU, would be resolved in considerable detail – but first we have to find them.