I've been working more on my Matrix setup lately and have connected Facebook Messanger, and Slack in addition to IRC, Matrix, Signal and WhatsApp. I also installed my own IRC bridge and connected it to a IRC channel I'm logged in since 2004. I made that room public so now everyone who has a Matrix account somewhere can join that room on my server and automatically be bridged to that room in IRC transparently.

It is a lot of work, but the bridges seem to be quite a killer feature for Matrix and for the first time I'm coming somehow close to a consistent UI for all chat solutions I use.