A.W.
I prefer to use Matrix in the orange bottle, but I color my hair every 4-6 weeks (a good friend is the stylist so it is not to expensive $40 or so) and I also flat iron my hair everyday(I do also use the purple bottle which is made for colored hair but I don't like it as much!!!) The times that I run out of shampoo and buy the cheap stuff (ie: sunsilk, herbal essence) My hair just doesn't have the same silky feeling that it has when I use my Martix. Now I do however usually buy it at Target, and I have been told it is not gaurenteed by the company. I have never had a problem when using these and so far I seem to have the same results.
As for the Pantene thing I have been told that also, and I have to agree!!! I guess if you don't do a whole lot of coloring, drying, curling, or flat ironing you might not need to worry to much about what kind of shampoo you use. But if you do a lot of any of these I would recommend using something a little more expensive.
This is all just from my personal experience, I have had my hair cut to the bottom of my chin and as long as 3 inches below my bra strap (oh and about any color you could possibly think of!!!). No matter the length I still feel the same way about the shampoo's.
Hope this helps you a little
A.