I’m not 100% sold on the Guardian vs a 5U Odyssey.
The basics:
The Odyssey 5U has better shields and better hull, while the Guardian does have an edge on maneuverability. You’re still flying a space-whale, so the Odyssey wins here.
BOFFs:
Hard one here. The Odyssey has 12 BOFF abilities, while the Guardian has and extra LT. Comm ability giving it 13 plus the ability to use Intel. That gives the Guardian an initial advantage. However, the Odyssey can assign an Engi to the Lt. Com post, giving it 2x Lt Com Engi abilities, which is a big plus if you are doing a EptS-EptW juggling build. It then boils down to does the console make up for this? Play style would dictate most likely.
Consoles:
The 5U gets 11 slots to the Guardian’s 10, and add in that you are using the Universal in one of the slots, the Guardian is put at a deficit. If a Fleet version with a extra console slot shows up, this would change things.
Starship Trait:
Guardian has one, the Odyssey doesn’t. (Yeah, technically speaking, you could have both ships fully developed and use it on the Odyssey)
My net feeling is that the Guardian is not worth it it you are looking to upgrade from a Oddy 5U, but definitely worth the look if you didn’t have an Odyssey. The starship traits add an interesting aspect to the mix, getting the Guardian and Eclipse traits on an Odyssey could be quite yummy.