I wonder if moving to the Skybell slim will work any better than the crap I have currently.
The short answer here would be maybe. It will all depend on the network it is attached to.
The original Skybell HD does have more demanding network requirements and requires better bandwidth and signal quality than the newer Slim Line. That was a purposeful improvement in the Slim Line. In general, if the issue is borderline wifi signaling you may see better performance from a Slim Line. If the signal is very weak all the time though, it may not make enough of a difference and networking solutions would be better.
In this circumstance the recent wireless signal quality history is very consistently low compared to what is required. For the Skybell HD nothing under 90% quality will typically work well. The signal quality listed in your history fluctuates between 75% and 84%. Unfortunately this is indicative of why your reported errors are occurring and would likely have some impact on a Slim Line as well.
If you have one available, a closer wifi access point for the Skybell HD would be a good troubleshooting step to see if a consistently higher quality can be achieved. You can also try lowering the HD’s resolution settings, but this has had minor impact in the past compared to network adjustments.