This is the best advice of all..... (hope you don't mind the edit of your quote)
ORIGINAL: JPMacG
My bottom line is this... try it and then range check, range check, range check.... Range check them..... Range check!...... range check....... the shortened antenna.
End of rant.
-- Not to mock or disrespect your knowledge at all, just a good point to drive home.
As I say I have found that it works for me, but this is also on smaller aicraft that the antenna is nearly 2x's the length of the fuselage.