I have had my LA for about 2 years now, purchased during Covid, so no testing models etc. But I've never regretted my purchase! Definitely a learning curve and doodling/practicing will help develop the muscle memory you need. Check the website specific to your machine as they might have all sorts of tutorials, cheat sheets etc to help you out.
I have been using Aurifil thread (cotton) since day 1 with no dificulties at all. Perhaps lintier than poly but I clean out my bobbin case etc with every change anyway.
There is a good printout called Troubleshooting Stitch Quality Issues from Quilters Headquarters:
https://www.quiltersheadquarters.com .