They both would actually drop the current roughly the same- the difference between the PTCR and relay based units is that the relay based will keep the start capacitor in the line a bit longer if needed due to genset bogging down- the PTCR based ones can kick out before the compressor has actually started.
Only the SmartStart and maybe that SureStart (which looks interesting) will actually lower the current.
Here's a forum thread on Sailnet with a guy from Dometic who did some actual tests on current draw on startup.
