Well as a double surprise the Empress arrived today. No shipping notice from FEA, so Im not sure when that might get here. The Empress is a very impressive little unit. Where the Diamond is intuitive and minimalist the Empress is less intuitive with more bells and whistles. The Diamond has this fat vintage vibe with what appears to be a slight hump in the mids, which works really well with my Thunderbird and my pedals. The Empress is not completely transparent but it doesn't impart a whole lot to the signal. It has a slight touch of warmth and adds articulation but otherwise appears to be fairly flat. The added clarity and articulation also works really well with my Tbird, which is sometimes a bit muted and muddy.
I love how the Empress has all these neat little switches and options and with the LED's it's very apparent what is happening to the signal. The Diamond has virtually no signaling about what is happening unless I overload the thing and the LED turns red. Most of the time it's green. So you have to rely on your ears. The Empress has red for gain reduction, green for input level and yellow for gain and input overlap, which is cool, and you can utilize the little switch to choose which you see. Ill definitely need to spend more time with both of these pedals but there are things I like about both and not much to complain about. I could definitely understand keeping both of them for different reasons.