Not sure if this addresses Neil's points, but I reverse-flow my LS, with the water going into the heads first. So perhaps the lower initial temperatures, plus the pressure drop from that water exiting the block, help prevent the issues stated with electric pumps. Thus far I've been very happy with my remote pump. Another feature I really like is that air in the coolant system is easily determined by a cavitation sound at the pump, that gets quieter as more air is removed from the system. Almost dead quiet when it's passing 100% water.