Just happened across this thread rather belatedly I'm afraid and just wanted to correct/supplement a couple of the answers:
First, the third-party (ie non-Davis) Vue/VP2-compatible loggers DO typically have data logging, ie what is referred to above as a 'storage' buffer. (Actually it's more of an intelligent summarising and storage function than a simple buffer, but it's a similar concept in practice). So all the loggers from the 'WiFi Logger' designer have storage and I believe that all the Meteobridge products do too.
If anyone is interested in the range of third-party loggers that are available nowadays then I have a summary online at:
https://www.weatherstations.co.uk/compatible-loggers.htm .
Second, to be clear, what Davis have discontinued from a Mac perspective is any further development of their Weatherlink for Mac
software. The USB loggers to provide the hardware interface to a Mac are still readily available and will continue to be so for the foreseeable future. You may still see the logger pack referred to 'Weatherlink for Windows' but the logger hardware is identical between PC and Mac - the only difference was the included CD/DVD software and Davis have now made this downloadable rather than included in the logger pack.
Although the old 6555 WeatherlinkIP
network logger is now discontinued, the third-party loggers assumed the role of a network logger providing data in the old binary data format. Any software that could accept a data feed from WeatherlinkIP should also be able to do so from a compatible network logger and to the best of my knowledge this should be true of WeatherCat.
The (relatively) new Weatherlink Live (WLL) unit has now effectively taken over from WeatherlinkIP as the primary Davis logger product. I would guestimate that probably 50% of our users buying a new Vue/VP2 station buy the WLL unit and not a traditional logger.
It's important to be clear about what WLL can do. Yes, one of its main roles is to upload data to the Davis weatherlink.com cloud platform, should you wish to use that service (the real-time part is free of course). But it also has a powerful
local API through which local computers & software can obtain a real-time data feed direct from the WLL unit. Other major Davis-compatible software like CumulusMX, Meteobridge, weewx and Weather Display is already fully compatible with WLL. It would be great to see WeatherCat introducing this compatibility too. Close to the top-ranking page in our Davis knowledgebase is people looking for Mac-compatible software so the demand is clearly there, but if their 'logger' is a WLL unit then currently they need to look elsewhere than WeatherCat for software..