An accident at any speed above a few KPH will do damage to the car of a serious nature whether it is equipped with a bumper or not. What you need to compare is a low speed hit on your bumper with a low speed hit on the sheet metal front end of your car. The former can be handled for the cost of a new bumper and lesser work to the areas where the bumper mounts to the front end. The latter without the protection of the bumper could add up to very serious bucks and major body work which only a shop could handle. That was the true purpose of bumpers, to reduce the cost of low speed collisions. I cannot say that for modern jelly-bean cars. Those plastic shrouds that have taken the place of the classic chrome bumper can set you back a couple of grand!
As for the gas heater the best comment I ever heard about them was from an old VW guy here in Ontario. He told me: " There are only a handful of people left who know how to get those things running safely. I know that you aren't one of them and I wouldn't even trust my own work ! " 'nuff said. Remove it and close off the gas lines with screws coated with Seal-All. ( available at CTC ) Dan (MY72BUG) in Goderich, Ont.
I'd rather have a partial bottle in front of me than a partial frontal lobotomy.