Hi Dragnlaw,
You know more about cooking than you think you do!
I really, really wish I could somehow help people to flip the switch on how they look at a cooking recipe, not a baking recipe though. Any soup, or stew, recipe is a shopping list and starting point only. I do not believe there is any step of that recipe, you don't know how to do already. I bet you already know that some Asparagus is more woody than others. I bet you have used a stick blender.
When I looked at that Spruce recipe, all I saw was-
Cook a veg. in water/stock, till soft, puree it with stick blender and finish with cream. That's it.
You already know how to -
Saute garlic without burning it
Cook veg in liquid until soft
Puree cooked veg.with stick blender
Add cream to something
Everything else like flavor that is up to the cook. What flavors does the cook like? If you love tarragon, add it! Low fat version uses skim milk and no butter. I would add a med. onion because I like that veg. with Asparagus and it will puree just fine and disappear anyway but adds a little sweetness and make it a tiny bit thicker.
You can make a similar soup using two pounds of either, Broccoli, Cauliflower, Potatoes, Frozen Peas, Frozen Corn, Pumpkin, Squash, Mushrooms, etc. to 1 quart stock. Cook till soft, puree, finish with cream....You can double or triple the garlic or eliminate it. Add an onion, or not...
*** Cool trick for cream soups! If you have two cream soups about the same thickness, Using either two ladles or two pitchers, fill the soup bowls by pouring at the same time, side by side, the two soups will stay on their half of the bowl! (They can't be too thin though.) This works even with Campbells Tomato and Cheddar soups. Red half, orange half. A fairly cheap experiment to prove it to yourself.
Blanch tips by setting the tips in a strainer that is partly submerged in the stock, when cooking the part you will puree, I want the flavor. Wish they would have said that in the recipe.... Recipes.......
To actually answer your question, yes, more Asparagus will have an impact on flavor and texture. Positive impact to me as there is just more Asparagus, so more Asparagus flavor and more fiber making the soup a little thicker which I prefer anyway.
I know there are things you make without a recipe. This can be done with this recipe if it can make sense to you.
If I locked you in a kitchen with those ingredients on the table, all equip. was available, except measuring devices and forced you to make Asparagus soup at gunpoint, ha ha, I guess, since I am an American and all Americans have guns. (Ha Ha since I don't have a gun.) The soup you would make, with NO recipe, NO measuring spoons or cups would still be delicious. I know this in my heart to be true! You would not be here as long as you have without knowing much more than a few things about cooking and seasoning.
I just wish you trusted yourself and your abilities as much as I do...
I await a tongue lashing if desired...