Because of your Axiom I was thinking N2K backbone. But really, your Axiom is stand alone until you install the converter, I suppose. I don't really think of the ST-1 as a backbone. Sure, you can daisy-chain the instruments, but the transducers are all cabled directly to the displays, and each display has such limited functionality, right? I guess you can use your autopilot to steer by the wind, which is a nice feature.
I have such a strong preference for the multi-function displays and that influences how I think about replacing the old single-function displays. I have 3 multi-function displays in the cockpit ... one is at the helm with the CP and the other 2 are over the companionway where they can be seen from anyplace in the cockpit. I can change the page of each display to show whatever I want to see, wherever I want to see it, and there is so much more information that can be displayed. The versatility of these multi-function displays is just off the charts and such an astonishing improvement. For instance, during a race start, I want the countdown to be viewed by all crew in the cockpit so anybody can respond accordingly. Just switch one of the (companionway) displays to the countdown during the start and then page back to VMG & SOG while underway (that's just one of a multitude of examples). I would look for any excuse just to get rid of the old single-function displays.
If I had a new autopilot, i would definitely have it on the network. But mine is old so I am satisfied with keeping it stand-alone. My intuition tells me that converters are the most likely cause for networks to go haywire. I don't think I will ever rely on any type of converter and instead make the whole system compatible. I hear stories of networks going haywire and I have also had a few issues with the newer electronics going bad, but to stubbornly hold on to the old systems feels a little like holding on to it based on fear and you'll be missing out on the great advantages that newer systems offer.