Not wanting to use propane in a GBB because it could explode is about as silly as not wanting to ride in a car because it could explode. Sure, if you drive your car off of a cliff, or try to set it on fire while driving: It could. But out of the thousands and thousands of people who own GBB's and are firing propane and green gas (as a brand), I have never heard of one exploding in flames.
But to answer your question; Not likely.
Sure, the weight of the slide has a factor in how weak a gas can push it, and how high the fps is: But what you should be looking at is the recoil spring and blowback unit. Not all guns are able to cycle HFC 134a, even with a plastic slide.
My advice? Man up and use propane.
Ár skal rísa, sá er annars vill
fé eða fjör hafa. Sjaldan liggjandi úlfur
lær um getur né sofandi maður sigur.