Medward
the reason i suggested a MPPT chargecontroller instead of one like you found is , that MPPT can "Track " down your 41.3 Volt panel towards your Battery voltage of 12 Volt
The panel specs are
Maximum power (Pmax) 210
Max. power voltage (Vpm) 41.3
Max. power current (Ipm) 5.09
Open circuit voltage (Voc) 50.9
Short circuit current (Isc) 5.57
The price difference of those two chargecontroller is about £ 50
I cannot tell you exactly how much power you will loose with that controller ( if he allows 41.3 Volt input )
But my guess is ,you loose about 100 watt or £ 300
Billi
