In 2006 I used the S-curl texturiser on my natural hair.
I am 4a/b fine strand and it loosened my texture.
Touch-up time could be pushed up to about 6 months with no problem.
My hair needed a lot of moisture though and looked natural if it was left dry.
I washed with "comb-thru" shampoo and conditioner, used S-Curl moisturiser over the whole head and "comb-thru" gel on the ends.
It worked really well in the summer.
My hair did not respond well to weekly flat ironing (no dc, and i did not have a lot of technique at the time so it was straight direct heat and led to breakage.)
But Yes, texturised hair can be straightened. blowdried, anf flat ironed. just take care of it.
The summer and the added moisture helped a lot in the overall health, appearance and length of my hair
When october came I wanted to change. so I switched gradually to a relaxer that had the same ingredient as S-curl (lye or sodium hydroxide). Motions.
I hope it helps with your questions.
here is a link of pictures with my texturiser.
http://public.fotki.com/sweetpuff/2006/
hope it helps
P.S.: sorry if i did not update my album as of late. busy year to say the least.