I really like to have one too to solve a problem and I like the automation provided by LE agents. What I hear occasionally is that you need to purchase non-Let’s Encrypt certs for some domains - for one reason or another.
The question is if this occasional whispers are more than … whispers.
Edit: removed details to keep the question generic.
Edit: some agents seem to allow changing the ACME server URL (e.g., certbot has a cmd line switch for that). The main integration difference seems to be the path to challenges (LE v other CAs), e.g., - acme-challenge v e.g., pki-validation