Very helpful and interesting thanks for posting
This article suggests that the 14.2V regulator you've found might be good for AGM batteries: http://batteryuniversity.com/learn/article/absorbent_glass_mat_agm(Edited) BMW Voltage regulator with parts that may fit into a Denso... preset at 14.2V
So that will certainly give a more accurate feedback to the alternator..... So I fitted a relay to parallel the main Brown & White wires that are connected by the Ignition switch. Splicing into these near the alternator to keep wire lengths short. There's an unused wire on the Ign Switch which can be used to power the realy on & off in tandem with the switch.