I'm fairly certain I'm going to buy an RSF Opel III, the other choice being a RSF Delta. With the Opel does anyone have experience with the catalytic converter? My understanding is that I'll get less creosote and longer burn times. I have to buy my wood so getting more heat out the wood is important. I'll be burning primarily spruce/pine as harder woods (birch/larch) are double the price. Thanks!