Ian, I've just been playing with those numbers a bit and they look good as far as I've gone. One thought on the "higher model"(or same for V2)requirement. If the primary characteristic of a "trade-up" is purchasing a higher cost model, could this be phrased as cost in relation to trade-in value, rather than than in relation to model numbers(say, the new model must cost at least 20% more than the trade-in value). For example, an older M50 or M60 with a trade-in value around $200-$300 could be traded-in on new M22s or a new VP160.
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Enjoy the music, not the equipment.