Flat Iron on Natural Hair (a small section with pics)

Okay the last time I flat ironed my hair was January 2012 when I was 5 months post relaxer (where has the time gone?!), click here if you want to see. I miss that length but not the thinness. Using my new Remington Keratin Therapy Pro S8590 Ceramic Straightener (if you want more info click here). I flat ironed a small section of my stretched natural hair. Look at the results:

I was truly shocked this was on 220centigrade, I can't wait to flat iron my hair and I was pleased at how straight my hair got considering it is type 4a/4b. I would definitely not be able to flat iron using such small sections it would take houuuurs! I used the brush chase method -I held the brush on the section of hair and pulled the straightener down (denimpixie has a good comb chase method) to get it super straight. I plan to flat iron soon, but I am slightly worried about heat damage. I obviously used a heat protectant before flat ironing (Elasta QP design silk), but last time I was natural I damaged my hair severely through flat ironing waaaay too much! I can't get addicted to heat again! So I may flat iron next month, obviously I will post results and may even film it. 

As for heat protectants, I want a new one! The choices are below:

(Left to Right):
1. Beautiful Textures Curly to Straight Flat Iron Silkener
2. Tresemme Heat Protectant Spray
3. Fantasia IC Heat Protector Straightening Serum 

*Update - my hair did not revert immediately when water was applied and yes I did have a mini heart attack! After an hour it reverted completely and the curl pattern is normal. It has definitely put me off flat ironing in the future, my heart was beating so fast! Also heat protectant no.1 by Beautiful Textures I have heard it does not work :/