Don't count on zero flavor from the warrior bittering. Neutral doesn't mean flavorless. 50 IBU from any bittering hop seems like a lot for trying to learn flavor/aroma hops. Unless your plan down the road is to make beers that have 50 IBUs of warrior at bittering addition.
Magnum is also considered a "neutral bittering hop" but, to illustrate my point, last winter I brewed a Helles with just a half ounce at 60 min, nothing else, and multiple judges, including two Masters, said that it had too much spicy/floral hop flavor and aroma. Point being that some will come through and it will interact with the late hops you are tryin to test out.