To get the glass off the frame easily & safely, I removed the earphone assembly & speaker, and the home button, then soaked the screen assembly in near boiling water and detergent - after a while, was able to prize apart using a credit card. After cleaning off old tape & then rinsing in deionized water and drying, reassembled - works fine & no hot hair guns or melting!!
Before you part the rails & slide the LCD out, ALWAYS check you have all the screws out. I accidentally left one in and as a result the lcd twisted slightly on this & was ruined. (bleeding around area of screw & white screen on rest). Never apply too much force or twist LCD as you slide it out as its VERY fragile and expensive to replace.
I've had problems removing non-apple touchscreens using the suction cup method - often the glass pulls away from the frame/lcd instead of the phone. On 2 occasions, I've had to gently lever up the frame/lcd with thin plastic sptum or ccard instead.
Also the thin glass of cheap touchscreens sometimes cracks when pulled with a sucker (if not already!) leaving 2 suckers!!
I agree they are very fragile! I broke off 1 EMF finger by pressing it down - wish i had read comments 1st! Phone still seems to work Ok, but gave me a scare.