This is most probably going to get me blasted by many but here goes. I have been matching the EP4200 cell longer than virtually anyone. I have direct dealings with the factory. The EP4200 cells are a good performer on the track but they have a few very nasty characteristics and they all revolve around high self discharge.
Any matcher trying to match these cells will strike the problem of a high failure rate in the cell because of the high self discharge. Turbomatchers take cells down to 0.8 volts during the cycling process even though most matchers use a 0.9 volt cutoff. This means that the matchers must stop and put a holding charge back into the cells after a cycle otherwise by the time they get back to this cell again there is a very good chance that it has discharged itself too low which means it will have lost a lot of runtime. Competition Electronics is producing a new Turbomatcher which automates the process of putting a holding charge back into the cells. This will make it easier to ensure the cells do not die.
I am not saying that this is the case but maybe Fusion is having the same problem and is not attempting to fully match the cells. First cycles will give an indication of a cells capacity and voltage. Maybe this is the reason for the LA packs.... simply put , group together cells with like voltages and runtime above a certain level.
THe EP4200 cell is good but not quite to the standard of the IB4200 cells. Many companies have tried and announced that they will be selling Eastpower cells (Orion for one) but dont seem to have progressed. The problem is the high self discharge and its associated problem of shelf life.
Even the Eastpower factory acknowledges the problem.