I have been a Wen girl for around 3 years now. This is my take on the product....
I'm 49. I have blonde, medium thick but fine hair. Wen has changed the health of my hair. It doesn't affect color at all. When Chaz says that you will have the same color hair after years of using his product, he is not lying. Now I have my hair colored every 16 weeks versus 8 weeks. Less processing means much better hair.
As Blonde vixen said, Wen can weigh your hair down, especially if you use the wrong version of it. Fig in particular will weigh it down, but I love Fig in the winter time, as it gives my hair a lot of moisture when the air is so dry. If you decide you want to try it, go with Pomegranate, which is the lightest version... not so creamy and has a bit of a lathering feel to it.
On the hair loss issue, when my perimenopause began, I lost a lot of hair. I read numerous books by trichologists and endocrinologists, trying to understand why this was happening. I personally do not believe that a topical product can cause hair loss. Would that it would be that easy to just change your shampoo and stop your hair from thinning when your hormones are changing. I believe that Wen has a great market for women my age. From 45 on, your hair texture and thickness begins to change, so you are very susceptible to Wen's pitch because you are looking for anything that will give you back to some degree the hair that you had in your younger days. Given the litigious society that we live in - I have worked in the legal field for over 15 years - so I know of what I speak when I say this, there is someone suing every company who ever put out a product. Some suits you know about, and others you never hear of. If you think you might like the product, try it. Once my hormones were balanced, my hair started to come back. And the hair that I do have is in great condition from using Wen. I also love the oils that he sells and the deep conditioner is better than anything that I have ever used.
Big but here - I don't buy that you have to use Wen exclusively. I know Chaz tries to make you believe this when he sells it on QVC, but what he should be saying is that you need to avoid sulfates in any shampoo that you use. In fairness to Chaz, when he first started selling Wen, sulfate free shampoos weren't that common. I think that his success is largely responsible for why everything is going sulfate free including drugstore products. I like switching up my shampoo/conditioner just like I switch up my skin care. Every third wash, I use Living Proof, Alterna, or Ojon.
I hope this helps you. Let us know what you think if you try it.