I've been trying to follow E-prime in my writing since 2020. However, Wikipedia notes:

Some scholars claim that E-Prime can clarify thinking and strengthen writing, while others doubt its utility.

As a source for “others doubt its utility” Wikipedia links to “The Top Ten Arguments Against E-Prime”, which I finally made the time to read.

Following the posts of a now defunct E-prime forum archived here, I found the full text of French's article, written for a 1992 symposium about the E-prime controversy. I'll summarize:

1. Since E-prime eliminates a whole class of statements (with “to be”), it may not improve writing. You can simply cut back on instead of fully eliminate “to be”.
2. Even if E-prime improves writing, you don't need to use it elsewhere.
3. Context often mitigates potential confusion around use of “to be”.
4. “To be” itself has a range of useful forms.
5. E-prime can make statements of identity more confusing.
6. A less absolute system of “general semantics” also solves issues related to statements of identity.
7. People could more easily distinguish uses of “to be” than eliminate them.
8. “To be” can serve similar to equivalence in mathematics.
9. E-prime can make abstraction more difficult.
10. E-prime overly prohibits statements that respect the principles of “general semantics”.

I find these arguments convincing, so I'll try to drop E-prime for now.