I know that a lot of people used regular leaded gas in their Coleman stoves back 20 years ago and as best I could tell it worked fine.

My understanding is that the new dual fuel stoves have some brass parts changed to SS but are otherwise virtually identical to the current stove designed around Coleman fuel. I have heard from a number of people that regular unleaded with or without alcohol works fine. I have not tried it personally.

One story I heard was that the main reason for the difference in price between the Coleman fuel version and the dual fuel version is that the duel fuel version costs much more for product liability insurance.