So the Whisper has bass that comes from front and rear, that must "involve" the room............right? How is it you note you dont like a speaker that fires from side or rear and yet you own one? Yes its Dipole bass but its still "involving" the room no doubt.
What experience do you have with the Quatro? Have you spent years listening to it? Because I have spent years with both speakers.
I know your a fan of Legacy, have reviewed and I assume recieved some tasty discounts on the models you bought after glowing reviews, thats cool and nothing wrong with that. But I dont owe anyone anything, I didnt get a discount of any sort on either speaker and I am not in it for anything more than honest experienced opinion.
Maybe you can get the boss at your review site to actually review this or any Vandersteen speaker. Surely such a well respected and otherwise well reviewed speaker is something you could learn more about to honestly discuss.
So there the OP has it, several opinions to mull over.............good luck on whatever you decide, like I said Legacy is a good speaker, Vandersteen is just beyond it IMO.