When comparing Fluid vs Adium, the Slant community recommends Adium for most people. In the question“What are the best Jabber/XMPP clients for Mac OS X?” Adium is ranked 1st while Fluid is ranked 6th.
Ranked in these QuestionsQuestion Ranking
Pros
Pro Webchat webapp services are connected to more protocols than desktop apps on the mac
Pro Separate webchat from your webbrowser
Pro Easy-to-use interface
Pro OTR encryption
Pro Open source
Pro Supports file transfers
Cons
Con Video chat will not work with FB Messenger
Even though the fluid app is supposedly a full blown browser, video chat on FB Messenger does not work within the Fluid App.
Con Hacky
Hacky solution for a lack of better desktop clients. Some webapps may behave strangely/ be buggy.
Con Appears to be abandoned
Not Gatekeeper-compatible, SSL cert expired, social media presence is ancient.
Con Lack of OMEMO encryption
the de facto standard for Jabber Texting [xmpp]
Con Release version has old OTR
The current release, version 1.5.10.4 only does OTR version 2, and version 3 has been out for a long time.
Con Lack of multi-resource message capability
No carbon copy, for example.
Con No antispam (built-in or by plugin)
It has no challenge-like antispam (such as seen on github.com/jesobreira/box-sentry plugin for pidgin).