Very much a hobbyist here and don't know how the professionals will use the FX Chains when inserted in the PC but I have Ozone 4 and no other really decent limiter so I've been using O4's Loudness Maximizer in the Master Buss as my limiter. Great plug-in but a PIA to open the interface and navigate to the LM module and adjust to taste. The FX Chains in the PC allowed me to map the 3 controls I use, Threshold, Margin and Character to 3 knobs that I named to my liking and now I have a sweet, smaller concrete type limiter, that I can insert into any PC on any channel or buss. The CPU won't be any less so I still need to use it sparingly but wow what a great feature. Kudos you guys.

Yeah I quite like this functionality as well; particularly the integrated input/output stages on each chain unit. Very nice to be able to drop in a 'simplified' version of any plugin anywhere in the channel strip, with customizable controls (not to mention the possibility of opening the full interface if you need to tweak anything else) and a built-in input and output stage. 

As a bonus (I think someone else pointed this out somewhere, but just to reiterate) you can drop a blank one in before/after the excellent Saturation Knob, which has up to now been hampered by a lack of gain control - using the gain staging of the blank FX chain to get it under control. Works a charm and allows use of higher saturation settings without clipping the channel.