...now, I just realized this in adding things up, but weren't we initially told that the 10% penalty would only be against points refunded (e.g. if you booked a 20,000 point redemption and then found that it was only 15,000 points and rebooked you'd lose 10% of the 5,000 point/fare difference [500 points] not 10% of the 20,000 [2,000 points])? I could be misremembering this, but I'm pretty sure that's what we were told (and/or what was at least strongly implied if not said outright).
Edit: Ok, this is a point of misremembering: It was Alan who suggested that the smaller amount would be the case. Anthony never answered it definitively (and there were several questions in the thread), but...at this point amid everything else I'm marking this half-off against Anthony for not clarifying sooner. The more of these little niggling details that pile up like this the more there appears to have been a definitive policy of obfuscation at AGR, though in this case (not unlike the BC award situation with Alan) I'm going to hold back judgment since, as there were a lot of changes to the program, things may have gotten mangled.
Edit 2: I'm piling on the "complaint points" here, but I've gone through and compared AGR's redeposit fee/change fee with the "big four" airlines (United, Delta, American, Southwest) as well as Virgin (since that's my airline-of-choice) as well as cases where they waive it. Also, I'm only looking at domestic flights since with certain narrow exceptions (basically Montreal, Toronto, and Vancouver) Amtrak is domestic-only.
Redeposit Fee/Award Travel:
-American: $150 domestic (waived for Executive Platinum)
-Delta: $150 domestic (waived for Platinum/Diamond Medallion)
-United: Complicated, but up to $200 (waived for Premier Platinum, Premier 1K, and United Global Services)
-Southwest: None
-Virgin: $100 (waived for Gold)
-Amtrak: 10-20% of award value (depending on time to trip, etc.; not the difference in fare)
Change Fee/Award Travel:
-American: None (as long as origin/destination remain the same, otherwise see Redeposit)
-Delta: Seems to be Same As Redeposit
-United: Complicated, but up to $100 (<21 days before departure) or $75 (21+ days before departure). Reduced or waived for most statuses, always waived for Platinum, 1K, and UGS.
-Southwest: None
-Virgin: Same as Redeposit
-Amtrak: Same as Redeposit (apparently)
Well, at least AGR is only charging Monopoly money for award changes...for now. *DUN DUN DUNNN!* Beyond that, it's a bit variable (on an expensive round-trip it would seem that Amtrak could be far more expensive to cancel/change than an airline, since award trips also lack the $100 cap on refund fees.
Edit 3: I'm going to say that I'm roughly 50/50 on which way this will ultimately break (e.g. refund fee on difference in prices versus refund fee on full initial price). I'm definitely open to this being an "agent error" plus programming issue, but I'm also fully open to the worse option being on the table.