You Get the Gist...
Anyways, this new update has opened it up and allowed FSE characters to take FSE in addition to TE signature systems. What????
But it isn't all good news. Unfortunately, the recent FAQ was not 'fixed' in regards to the Earth Caste Pilot Array. This new update still lacks the language, that the original supplement had, which allowed Riptides to take signature systems. So in the current rules a Riptide still can't take an ECPA or the Seismic Fibrilator Node (not sure why you want anything else).
Somebody needs to come up with a new name for the souped up versions of commanders this union will produce.
Buffmander 2.0 = Iridium, DC, VRT, Stims, CCN, M3S, Warscaper Drone (marker), Talisman
FBC 2.0 = Fusion Blades, VRT, Iridium
Although the Buffmander has a lower level of effectiveness in this day of Drone Net and Dawn Blade detachments...
It appears that currently there is a conflict of rules with the GW (What? no! They would never!)
Depending on where and when you buy this supplement, the signature system rule change may not be there.
From what I have heard, if you bought the book in an epub format or if you bought the physical book, you can take both siggie systems. However, if you own the iPad version it has the same wording as Mont'ka: either/or.
Hopefully GW fixes this quickly, and since people with physical copies of the new supplement have confirmed the change, I'm going to assume the FAQ will be in favor of the change.