ok..so u asked for my opinion and here it is..
if you want to do the flat black which you obviously do, without a doubt, go with the vinyl wrap. they are relatively easy to apply and i have a friend who vinyl wrapped the roof of his gto who could come down to help if you would like. you can wash, wax, and claybar the vinyl wrap. also, say for example you got in a fender bender, do you want to be the guy that says to the body shop, just bust out the rattlecan? no you dont. if anything happens, the worst possible outcome is that they spray ur car glossy factory black again and then we go ahead and wrap it again. Also, with the economic downturn, if anything bad happens to ur financial situation, you will want to know that you can still sell it if you need to. No one (and i repeat NO ONE) in their right mind would want to buy a rattlecanned G6. All that would do is point out to the possible buyer that the car is molested and would dramatically decrease the sell-able price or even make the car impossible to sell. I say, 100% that what you need to do is vinyl wrap it. Just make sure u use the weather proof and wax-proof stuff so that you dont waste your money.
Thats my 2 cents.