PM'd ya... I do not own the Choate. Why wouldn't a +1 and a +2 be for the 18-1/2"? Hanging stuff out there on the end of your magazine tube as far and as heavy as you can make it is not always best, especially unsupported. I swapped my nice Max100 +2 for a Vang Comp +1.
Choate has been around since I was a kid and have always made cool, but not always the best, products. I presume theirs and even a TacStar, maybe, if they even make these, would be OK (unlike my last Vang Comp extension -- I regret not getting an S&J most recently -- maybe Mr. Vang is just getting too old!).
This above all: to thine own self be true, And it must follow, as the night the day, Thou canst not then be false to any man.