I don't think the M2's would have better off-axis response than a VP100 unless they are sitting upright (re: Robb's suggestion to put them on their sides but with the tweeters on opposite ends). I think Robb's setup with them vertical above and below is buttery and delicious.

I think the VP100 is really a pretty great speaker. Haven't heard the VP150. I'd certainly install two vertical M2's, but it doesn't pass WAF at my house.

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