I like the Cyrix, a very effective and simple product. May I suggest that the 30 sec connect wire for emerg starter battery boost have more intelligence to make it more versatile, in particular....
Connect to a double throw 3 position switch to enable the following operating modes:
+12V: Cyrix closes for starter battery boost
Open cct: Cyrix operates normally
Gnd: Cyrix never operates, ie. disabled
Sometimes it is handy not to load the alternator with house battery charging because of other parallel loads, so it would be good to be able to disable the Cyrix at the flick of the switch.