I too have had the starter problem after going with the b in b, when I finally got sick of it being hard to start I upgraded the whole power/ earth feeds to Copper
Earth- 3x 2ga cables (attached at boot, under rear seat and then to the fire wall with 4 straps to the engine)
power to 2x 2ga (1 via a breaker and kill switch and the other was straight to the starter in Kevlar sleeves)
Started every time after a short stop but was hard to start after sitting, found out my battery had a dead cell (over charged when I borrowed a mates charger that didn't auto shut off) after a new one I never had an issue,
Maybe get a multimeter and check what the voltage does under cranking load with just the GSR battery, if it's a dead cell the voltage will drop significantly