Roxy54 - it's hard to know. I had some clues from an acquaintance who had been personal secretary to Adcom's president in the day. She advised me to find an 'original' and helped puzzle it out.
It's not uncommon for a manufacturer to create a worthy product, get good reviews and dealer buy-in and then erode that foundation via lower cost components, sources and so forth. I was personally chagrined to see some late Thiel CS2.4s that didn't hold a candle to the original Lexington variety. So the world goes.
I suggest keeping an open mind to the potential of the GFA555. Nelson still loves it as designed; and we have certainly taken it up a few notches.