The Doheny Discovery and the Nautilus Plus (S300) have gotten good recent reviews from TFP members. A smaller robot might do the trick for you as well with that pool volume. I don't have any first hand knowledge but perhaps a Dolphin S100 or similar would be enough for your pool. Use the search box in the upper right to find threads about robotic cleaners.
You can do a little better than $675 today if you want, on the first (refurbished) option. The Active 20 is the same as the Discovery. Now it's $599. It was $499 briefly, then $549 last week. The new Discovery's were $649 last summer, though now are Reg. $799. But it's all about what the price is when you want to buy, not what it MIGHT be some other time. My belief/understanding is that Poolpartz.com is an authorized seller of these refurbished units (work done by Maytronic's certified technicians, not Poolpartz). So you then do fall under the "OK" group of online buyers for this particular product. Though repairs do need to be mailed in per the documentation. I think that Poolpartz.com has an agreement with Maytronic's to take their refurbished unit off of their hands and handles those sales (or at least a lot of them.) It's an interesting site to watch the prices fluctuate on over time.
I bought an Active 20 at $499. Happy so far. Just one occasional issue of getting stuck on a bench. Still a huge improvement over a pressure cleaner.
Basically the same yes, but they do have different basket styles. Two clip open containers on the Nautilus Plus vs. one bigger basket style on the Discover. That link is really pretty good, though not complete and not completely accurate.