my buddy and i were just talking about this last night out on the boat. he had the tsunami pump for his bags and hated it. note: i have no experience with the with fly high so i can't comment...Thant said I love my sumo sacs and pump, the one way valve is the sh#t!! i can fill and empty sacs with out leaking more than a couple drops of water at most. never had a big enough problem with the pump not priming to post about it on WW, it's simple if it stops pumping unplug it and plug it back in, thats it!
if i was buying bags to plumb into my boat i would buy fly high bags because there are way more options in size and the bags are pro a little thicker. but for a bag or two to just throw around the boat my money is with sumo...