Anytime you add weight to the front of an arrow or decrease weight from the rear (or both at the same time) you "soften" the spine.(and increase FOC)
The heavier the weight is up front the harder it is to getit to start moving against the flex of the arrow shaft and the weaker it will make the spine of the arrow. The shaft will flex more and easier. Take it to an extreme to see this effect........picture a 1lb broadhead on the tip of that arrow , when the bow is shot and the force is applied to the shaft it will bend like a noodle or possibly snap trying to get that weight to move.
By adding a heavier tip, or removing weight (in the form of feathers vs vanes or a lighter nock) in the rear you achieve this effect.
In the opposite direction anytime you add weight to the rear or decrease it in the front(or both)you STIFFEN the arrow spine.(and also reduce the FOC) With the weight at the rear of the shaft there isn't as much resistance up front to push against and the shaft will flex less and act stiffer.
This is the reason most arrow charts want to know what weight tip you will be shooting on your arrow and at what length.
I'm not a big Whisker Bisquit guy but I would think if I wanted to shoot anything through it I would want feathers anyway. They offer less resistance when they come in contact with any surface (The reason Traditional shooters use them) hold their shape nicely and still guide an arrow just fine when they get a little frazzled looking.
Feathers are a lot tougher than you think, and even after lots of practice they don't look exactly like the day you fletched them, odds are they still fly like they did that day.
Again if it was me I would use feathers, beat the ehck out of them practicing and reflecth just prior to the seaosn if they were in really rough shape. (But then again I fletch my own so its pretty cost effective and easy for me to say that)
Depending on which broadhead you choose the vanes you mentioned will most likely guide your arrow just fine but as you already noted they are going to be heavier but will probably hold up better through your WB rest.
Maybe I just have a touch of old school in me but if I have an aluminum arrow on my bow it will have some sort of feathers on them everytime.