I tried to reply earlier but had site issues.
I use henna, and haven't found it to be drying at all. In fact, my hair has returned to its natural oiliness since I quit using chemicals (commercial and salon dye).
My hair is naturally red, but the henna adds intensity I'd lost as I've aged
. It's also really easy to slap on my hairline when I notice grey shining through.
Only one stylist talked about henna with me, and he gave me such a bad haircut, I've tuned out the details.
I like it for its ease of application; having control over my own color; its value; and the vividness of color I get.
(RCW persuaded me to use it, and she was right. Credit where credit is due.)