sounds about right
My first (and and still favorite) custom GP is an 84" x 3.5" with a 20" loom, un-shouldered. My 3-piece travel GP is also 84" x 3.5 but has soft shoulders and I agree there are times that I like having that kind of “index”. Other times the shouldersort of bugs me, but that could just be because I have used the un-shouldered one for so long that I am used to it.
Look at it this way, if you are uncertain: go with the narrower loom and the shoulders. They can always be shaved down and the loom widened. That’s one nice thing about a wooden paddle (besides that they are light and beautiful and float).
One caveat
I might be a rare case, but I don’t imagine I’m the only one. I developed forearm tendonitis due to overuse of technology at work. I found that my shouldered GPs exacerbated the problem.
The shoulder on a GP is essentially a reverse bend - the opposite of a bent shaft Euro. Your pinky is elevated above your forefinger.
Not a great position if you have any pre-existing forearm conditions.