How are your palms doing? I planted several within the last several months, and so afar they are all hanging in there ok. I have a couple of windmills that have bent fronds, but my back yard gets a fair amount of wind, and it bends them. I think they are healthy enough, and keep showing new growth, I probably wouldn't buy them again. My other palms are more resistant to the wind, and look better. You happen to be near a guy that grows alot of palms. I've bought a few from him, and have been impressed. His website is:
North Texas Cold Hardy Palms
I have no affiliation, just a satisfied customer. I also bought a few palms from the place in McKinney mentioned above, and they are doing well also.
FWIW, I had one CA Fan palm I put in , that immediately went into distress, I mean it looked terrible! All but 2-3 of the fronds turned brown, and soft. Upon investigation, I found the ground soaked. drenched. I found there was alot of overspray from a new sprinkler head I put in, and that I had too many drip emitters there also. I spread them out a bit, and readjusted that one head. I then pulled the palm, and replanted with fresh dirt all around it. So far it is doing well.
I have mine on drip lines, like you do. I've used the Carl Pool stuff, and it seems ok. What seems to make a huge difference in my beds is the use of Garrett Juice and Compost Tea. It's kind of a local thing here in the metroplex I think. I can't tell if it helps the palms or not, but it brought some other new plants, especially 4 large wax myrtles, I put in back from the brink. I've been using it for about the last 2-3 months. Sounds silly, but most things seem to flower within 2-3 days of me pouring this concoction around the bases. Might help, I don't think it can hurt.
Hope your plants are doing better in this cooler weather!