I usually prefer the pumpers but for the only reason being I can place the fuel tank any place I like. I usually install them over the CG of the plane and don't care about them being lined up with the carb or close to the fire wall. I have a couple of the .91s without the pump and they are outstanding engines, tank location is the only difference in the set up. A pumper has a regulator so when in the air they aren't supposed to go rich or lean, most the time this is true. Like your club members stated, the pumpers are great until you run into a pump or regulator problem, I'm having a problem with one of my 1.20 pumpres now and it is really a pain trying to sort it out so there is a lot of truth to that. The pumps are a one piece unit and can not be rebuilt. If you have a diaphragm problem in the regulator OS will not just sell you a new one, they have you send the complete carb into them for service. I just did that, cost a bunch for that $2.00 part to be installed. If I am buying a new four stroke I have been buying YS, better prices and much better engines. I can buy every part ever needed for them from there service center and it dosen't cost an arm and a leg like with an OS.