That is a big fallacy. Having available source code does not warrantee any better security. As samples, the 3 years Interbase/Firebird hardcoded administrator login or the “goto” issue in Safari certification chain.
About 99,9999% of security issues are found with post-mortem tools and compiled code analysers.
Also late to the party, and just wanted to say I appreciate all the discussions here about alternatives to 1Password, even though we’ve strayed kind of far from DEVONthink topics :-). I’ve been a paying customer of 1Password for myself and my spouse for years, but I will not be upgrading to v.8 because (1) version 8 no longer supports local vaults and (2) subscription-only pricing. I’ll use v.7 until it stops working and then look for an alternative that will work on Windows too, and the discussion here provides some nice starting points for alternatives to consider.
I’m also a 1Password user, i use it free for the whole family because my employer has an Enterprise license (the family license is included). I do not like the step 1Password takes by moving to an Electron app.
I not against Electron app, but i also do not like them running in the background all the time, which is the case with the current 1Password 8 version. I also see 1Password as a convenience application and i do not want it to use ‘to much’ resources on my system.
With the changes to KeyChain in MacOS Monterey i will probably move to the MacOS native password manager because it adds a better UI to manage passwords.
I can understand a company like AgileBits to move to Electron because they are multiplatform. Many companies that are creating mutliplatform applications seem to choose electron these days. Unfortunately most of the time these applications do not integrate well in MacOS. It’s probably the reason why i like applications like DT (and OmniFocus, and many more) so much because they are native MacOS App and their developers choose to develop for MacOS. Some people may find these applications ‘dated’ because these are not tools with flashy UI’s but they work really well on the platform for many of their users. 
I’m also a 1Password user, having used it for many, many years. But I do not like that going forward, 1Password will be subscription based. So once 1Password V8 is released, I plan on moving to Bitwarden. The reviews of it (just about all positive) sound excellent.
Bitwarden is fantastic. I moved from 1password years ago when they jacked their prices up, never looked back and like it better. Electron apps are terrible, they hog resources and are constantly acting flakey. The more electron apps I run, the worse they seem to get.
Bitwarden is also an electron app, but it works fine and is a lot less expensive compared to 1Password.
Ah yes. My comment was meant more in general. Slack would be the biggest irritant in that realm.