My point is that combo pricing tends to reward new customers (and procrastinators) while at the same time penalizing existing customers who jumped right on the pre-order bandwagon and thereby missed the 30-day window of opportunity to upgrade.

In general, a repeat customer is many times more valuable than a new customer. A repeat customer costs less to acquire and generates much more sales volume over time. Of course it's also important to attract new customers, but common sense would suggest at least giving your repeat customers the same discount deal.