On Shorai's website the only 18 battery I can find in a case #2 is a 6 volt? With the service the 2 of you have had (30k) it may be overkill anyway. I am sure the 14 will work just fine since the 9 has.
I like the looks of that Anti Gravity. Anyone have any experience with them? This thread has been very helpful and I just need to say, "Well Played" !