The ObserverIP should be considered outdated technology. It is not a very reliable device, especially when you try to expand it with the likes of Meteobridge.
The WS-1550IP is is not without a console....the little black box is a console. It just a console without a display. Semantics and interpretation as I know we are saying the same thing and I know you understand it well. I just wanted to say that the ObserverIP is similar is basically doing the same thing as what is built into the display console models.
Your preference for Ethernet over WiFi seems odd. The WiFi display consoles have the flexibility of being placed anywhere within WiFi coverage. Besides WiFi coverage should be easier to resolve then that to run Ethernet cabling to the router in many situations. I personally don't see the advantage of the ObserverIP being an Ethernet connected device. I see it the other way around, that the WiFi connected display console is the one with the advantage...so that you can have that display where it can be most visible to you. The ObserverIP has no display and that right there makes it less useful.
If you truly have no need for a display then I would recommend the Ecowitt GW1001 or GW1002 or GW1003 instead. These come with the GW1000 and are far superior to the ObserverIP.
As for Ecowitt and dealing with China...their support has been incredible. They are very responsive with their support. Ambient's support is also exemplary.
There are reasons to choose Ambient and there are reasons to choose Ecowitt.
Here is my take on not the similarities but the differences...
Ambient:
Choose them if you want access to the Ambientweather.net over Ecowitt.net. The basic differences between them are that Ambientweather.net has support for Google Assistant, Amazon Alexa, IFTTT and an open Internet API for other purposes. They also have a new map interface with forecasting and they are working on even more future features that are not yet announced.
Ecowitt:
Choose them if you want access to Ecowitt.net instead of Ambientweather.net. Although they don't yet have the features that Ambient has developed they do have more sensors that they support.
But the biggest reason for choosing Ecowitt over Ambient is to be able to configure exactly the station that you want with more sensor and console choices. Ecowitt is basically the direct sales arm of Fine Offset. With Ambient you are basically limited to only the parts that they choose to carry. With Ambient you are going to be limited with firmware that is purposely restricted from using other sensors that they don't carry. With an Ecowitt console you can use any sensor even sensors from Ambient.
*** But ultimately there is a way to have access to both Ecowitt.net and Ambientweather.net. I have access to both with my station configuration. This is something that with the correct parts is available to anyone. This is how that is accomplished.
If you start with an Ambient branded console that only reports to Ambientweather.net, you can add Ecowitt.net support by simply adding an Ecowitt GW1000 as that console will pick up any of your Ambient sensors. The GW1000 will send all of your Ambient sensor data to Ecowitt.net
If you start with an Ecowitt branded console that only reports to Ecowitt.net, you can use the Ecowitt GW1000 with a Meteobridge (with the added Ambientweather.net license) or a Ambient WeatherBridge and then you can upload to Ambientweather.net. All your Ecowitt sensors will then be picked up by the GW1000 which will be sent to the Meteobridge/WeatherBridge and then get uploaded to Ambientweather.net.
Out of those two configurations the best one is the second one, where you use the Meteobridge/WeatherBridge to upload to Ambientweather.net because your entire station has the capability to use more sensors that Ambient doesn't carry and to see them on the HP2551-C display console.....because they won't all show up on the Ambient WS-2000-C display console.