From the page on the test -
https://greenbankobservatory.org/successful-test-paves-way-f...> Using the information collected with this latest test, the participants will finalize a plan to develop a 500-kilowatt, high-power radar system that can image objects in the Solar System with unprecedented detail and sensitivity. The increased performance also will allow astronomers to use radar signals as far away as the orbits of Uranus and Neptune, increasing our understanding of the Solar System.
> “The planned system will be a leap forward in radar science, allowing access to never before seen features of the Solar System from right here on Earth,” said Karen O’Neil, the Green Bank Observatory site director.
That use of the word "unprecedented" and looking at Uranus and Neptune suggests to me that it will go further than Arecibo did... three decades ago.
https://ui.adsabs.harvard.edu/abs/2000DDA....31.0803N/abstra...
> In October 1999 we obtained the first radar images of Saturn's rings, using the recently-upgraded Arecibo telescope operating at a wavelength of 12.6 cm. The opening angle of the rings was 19.9o, and dual-circular polarization data were collected over a period of 5 days. The resulting delay-Doppler maps have a range resolution of 100 msec and a frequency resolution of 2 kHz, corresponding to a spatial resolution cell of 15000 x 2000 km. Previous radar observations (e.g., Ostro et al. [1982] Icarus 49, 367) demonstrated the rings' high cross section and depolarization ratio, but did not yield 2-dimensional images.
The key thing with this is the radar astronomy rather than radio astronomy.
The tracking is likely what's at play for the Uranus and Neptune though. https://en.wikipedia.org/wiki/Arecibo_Telescope
> The round trip light time to objects beyond Saturn is longer than the 2.6-hour time that the telescope could track a celestial position, preventing radar observations of more distant objects.
Uranus is about 2.5 light hours Neptune is about 4 light hours from us. Double that for the round trip time.
The primary interesting part of this is getting the accurate ephemeris of near earth asteroids.
https://www.lpi.usra.edu/meetings/acm2008/pdf/8285.pdf
> Arecibo Doppler measurements (2380-MHz, 12.6- cm) of asteroid 99942 Apophis, obtained in August 2005 and May 2006, have been combined with optical astrometry reported through August 2006 to produce a new orbit solution.
https://www.sciencedirect.com/science/article/pii/S001910352...
> During these encounters the Arecibo and Goldstone radar stations collected seven Doppler and 22 delay measurements of Bennu. For a general description of radar astrometry see Yeomans et al., 1987, Ostro et al., 2002. This wealth of ground-based tracking data allows an extremely accurate description of Bennu’s motion (Chesley et al., 2014). The trajectory of Bennu is deterministic until 2135, when a close encounter with Earth leads to strong scattering and makes the knowledge of its future motion statistical.
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So it looks like Green Bank will have improved transmitter and tracking. It won't have quite the sensitivity of Arecibo, but it's still one of the more impressive resources.