As it turns out, you cannot claim a GST refund on checked items unless you are directly departing on your international flight. I spoke with Customs yesterday (and then netted it out this morning) and learned that they won't "sight" your items in one airport and then let you claim in another, so if you are connecting (and have liquid items in checked luggage), you need to reclaim your luggage in your city of international departure, have it "sighted" by Customs outside security there, re-check and then have your claim processed after clearing immigration. Given my time constraints, that was very unappealing so I ended up leaving the $150 on the table - rather a bummer. The reasoning is that you could have the items sighted at your initial departure and then never re-check them, thereby having them never leave the country . . .though if I'm holding an international boarding pass, that seems like a bit of a stretch but so be it.
It did, however, leave a bit more time for flounging (I'm totally adopting that term).