The only issue I've seen is when I want to add someone who's only WhatsApp to a Signal chat, which has happened maybe twice until they also joined.
Personally I feel good about taking even a small amount of Comms out of Zuckerberg's clutches
* Messenger for family and some friends * WhatsApp for group chats and most of my friends * SMS for older family members * Signal and Telegram for a select few privacy-conscious friends
And at least one family member uses three of these, and it's a toss-up which one he'll use at any given time.