The FACTS ...
1. Yes, I tend to speak without checking my facts, so ...
2. This time I have thoroughly done my research. -- before me I have the CASINO VERITE printout [for 2D, S17, 75% Pen, NoDAS, NoLS, 8-1 Spread] <> and The ORIGINAL Hi-Opt II document by Braun/Humble and the Hi-Opt II Indiuces from "Aces and Faces" by the late Rob McGarvey. Thus I am quoting 3 independent sources, NOT my own ill-informed subjective opinion.
A Verbatim Quote from Braun/Humble p.8 "Take Insurance whenever the true count equals or exceeds 6 ... For greater conservatism raise this requirement to 7 or 8."
The above seemed absolutely bizarre to me as Risk Aversion would seem to indicate taking Insurance at a slightly LOWER index, as you have so clearly pointed out. Incidentally multi-deck games are barely mentioned although the document was re-copyrighte frequently through (at least) 2001
When a well-regarded Green-Chipper ran off the S B A Indices for me and produced the R.A. Index of +5 (and a regular Index of +4) I questioned this - but did not receive an empirically satrisfactory explanation.
Finally, I checked with "Aces and Faces" (because there is a dearth of published Hi-Opt II
indices.) On pp. 175-177 the Surrender indices for 1,2 and 6 decks are given as +3, +4, and +5. They are standard, not Risk Averse.