We have two ECDM,s so feel free to pm me with any questions I would not be as concerned about a few grams on the mtn tandems as you want serious durability. Chris King hubs are the only way to go. Alex at MTBtandems is a great guy and super resource on these bikes. One thing to be aware of is that age bike the rear triangle has some tire size limitations so evaluate that before you buy tires. We have only went down on the road tandem once but the mtn tandems are another story with more then enough crashes at Moab. It is crazy what can be ridden on one of these and the stokers get way more respect from single riders when they see you on the trails. Our basic builds are CK hubs, thomson posts, hope brakes. White brothers forks sram grip shift and 9 speed drivetrain , middleburn cranks, wtb rims, egg beater pedals (shimano spd pedals do not wrk in Moab red dirt sand) good luck on the new build and bike.