For a high efficiency setup I would not prefer a modular pack to begin with. I do solder the packs in series, including balancer cable. Unfortunately the specs of a pack don't mention the weight of the leads. Keep in mind SHV setups have thinner dia wiring and smaller connectors. Lower C-rated packs are lighter too.
Don't get blinded by the inner resistance of a motor. If the voltage is higher, the current will drop which reduces heat waste and increases flight times. An other side effect to be noted is you can recharge the cells with high current and continue the flight without the classic cooling down time of approx 1hr we used to do to avoid a demagg.
On a 2007 project I was able to recharge my pack within 8 minutes and take off for the next flight. At a turbine event the recharge time has been used to create a time gap for turbine flyers 3 times in a row
you cannot do this on a High Amp/Low Voltage setup.
if the motor stays cool, there is no reason to add more iron unless it lacks torque or you have to start doing math with other fan+motor diameter with identical FSA to increase torque. That's why the 80mm class has been introduced.
If I were to design an other speed edf racer I'd go SHV for sure. Not only because of eliminating heat waste but the design layout of the airframe would not be "in the box" to start with. Unfortunately, there are no high performance edf jets available to match high power setups. A good edf jet design is a key factor as well, not only the drive system.