I snagged this freebie, and I happen to have an original vintage 160 (I found it at a junk shop 15+ years ago. Good luck getting one now... the prices went nuts on these and I'm going to sell mine soon, before it stops working!). My thoughts after a few days:
This freebie is a good plugin, but I don't think it's a strict emulation of the 160. Perhaps inspired by? Or based on another DBX unit I'm not familiar with? I don't know.
It's more flexible and harder to dial in than the hardware. You can get it to do more or less what the hardware does, if you set it up right.
Sound quality is very good. However, _none_ of the plugins sound exactly like the hardware 160 to me in character. The tone (frequency response) is off, and the compression behavior isn't quite the same. Apparently it's one of the more difficult compressors to emulate? On the other hand my unit looks like it's never been serviced, and is pretty beat up, so who knows what it sounded like new?
Best way to describe the hardware is extremely even and stable compression. Every one of your snare or kick hits going through it are robotically evened out, and craploads of smack and punch are added, with an entirely predictable, stable, release and attack timing.
All of the 160 plugins bounce around a tiny bit on the attack, sometimes getting clicky on some of them (the hardware is impossible to make clicky... it magically turns the transients into solid smacks, not clicks). The release also bounces around a touch on all the plugins.
Another thing the hardware can do is graciously handle complex program material such as drum bus or even mixes. The Waves perhaps comes closest to doing that, which is funny because generally speaking Waves compressor emulations are always amongst the worst on the market to my ears. Their dbx really ain't too bad though-it behaves pretty well. Reality check: all hardware comps handle complex material better than plugin compressors, so picking on the dbx plugins isn't very fair, it's just that it's further off to my ears than the typical SLL bus compressor plugin or whatever (most of which do a good job)
Tone-wise the Softube has the Waves beat though. It's not like the hardware, but it's a very good sound.
Quite hard to pick a winner between UAD, Waves and Softube on the DBX comp front. They are all noticeably different with pros and cons.