[Stealth]

Okay I just did about 2 hours of research comparing the SKD PIG, Mayflower and the TAG/Shellback Banshee.

I have the most on-hand experience with the PIG so I'll speak on that first: The SKD PIG is probably the "smallest" profile out of all 3 but only if it's running the elastic cummerbund. With the MOLLE cbund they're all about the same. It's a bit overbuilt for a plate carrier but the ease of adjustment puts it above the rest in that regard. There are quite a few options for the PIG like the elastic cummerbund which slims down the rig significantly but that's at an additional cost. The back venting on the PIG is also superior to the other 2 rigs below but none of the 3 offer the mesh backing

The Shellback looks like the best bang for the buck and I *almost* pulled the trigger on it, but did some due diligence and found out that it's twice the weight of the Mayflower, but probably about the same weight as the PIG or less. Most people will like the front and back velcro for morale patches and to be honest it'll serve 95% of all people looking for a low pro plate carrier. The only thing I noticed is that it doesn't have the internal velcro so you can't really adjust the height of the plate inside the carrier like you can with the PIG. It DOES allow you to run the rig without the MOLLE cummerbund but I noticed that the removable nylon straps aren't bungee so it may not hug you like the bungee cbund hugs you like the PIG.

Now the Mayflower APC is the lightest out of all 3 by a far margin at just over 1lb with no plates, but the angle of the shoulder straps may not work for everyone. While there are no elastic cummerbunds available for the APC, I feel it doesn't need one as the nylon used is only 500D and the whole rig is very lightweight.
I had a tough time finding the right size for me. I'm 6'2" 180lbs and apparently I wear a Small/Medium APC with a Small cummberbund. The whole point of me getting this plate carrier is for a slick setup so I opted to go with the medium plates as mobility was paramount.

The Ferro one looked promising but then I noticed that there's nothing in stock and you have to sort of pick and choose the options you want so by the time you're done you're looking at a rig that costs about the same or more than the PIG, which has been proven to work well for the past few years. Like Gato said, there aren't that many innovative features on the Ferro rig but it DOES have the mesh back which could be huge for extended engagements in hot weather.

All 3 rigs will ride high enough so that you can run a battlebelt or a standard belt setup. However, that's entirely dependent on what size plates you run. If you're a shorter guy and run large plates, then that will interfere with your 1st line belt. Keep in mind that most of these rigs are going to be only as big as the plate you're using.