Tony originally pointed me towards this company's limiter, which I demoed and bought, later adding their compressor to my toolbox. More recently, I've spent time demoing Syrah (adapative creative dynamics processor), Epure (parametric EQ), Solera (broadband dynamics processor) and Alchemist (multiband version of Solera). The demo versions don't have time expiry, don't require an iLok, but also are missing important features such as the ability to save settings, automate settings and stop being adjustable after 30 minutes of use.
Some features which set them apart from the competition are:
1) the use of A/B recalled presets with a morph slider that allows one to easily test two different settings, or slide between the two to find a new compromise setting. This slider is automatable
2) Hysteresis - a Flux innovation that allows the dynamics processing to operate on the input signal level rather than the threshold level. Normally, when a signal level drops below the threshold setting the dynamics processing ceases. Hysteresis allows the processing to be relative rather than absolute. I find it difficult to describe but playing with the knobs shows the difference
3) Angel's Share - another Flux innovation which "produces a slightly less compressed and more open sound by relaxing the compression ratio applied when the dynamic range rises." (SOS review excerpt).
In terms of quality and innovation they are on the top shelf. The main downsides are the price of the more complex tools (though worth every dollar) and the use of iLok for product security (an additional cost and clunky form of anti-piracy). Flux do sell their own security dongle so an iLok is not strictly necessary but a number of other high-profile companies (Waves, EWQL) currently use iLok as well, so it's more widely useful.
They market themselves as mastering grade tools, and I think Tony would testify to them being among the best for software solutions (though not of course in competition with high quality hardware). If you are in the market for excellent dynamics processors do yourself a favour and test drive Flux.
They also provide two very useful plugs for free - a stereo tool and a transient shaper. If nothing else, download these two and add them to your toolbox.
Reviews in Sound On Sound:
Solera, Epure, Limiter, Compressor, Expander, DeExpander