At the time I never QT'd coral or fish. I'm not so sure it would have helped me at the time since I didn't really know what to look for in the first place (would I have noticed ick or a couple flatworms?).
I actually just setup my first QT last month. My most recent fish (angel swallowtail) was going to sit in there for 4 weeks prior to going into the display. After two weeks she developed popeye, and she's currently being treated. Great time to start a QT, eh?
The alk spike was because I had ran out of 2part for my dosers. So I quickly mixed up a new batch and manually overdosed the tank (I usually let it rest overnight to settle). Alk spiked from about 6.5 to 9. For a couple days the tank was in rough shape, I thought it was alk burn. However, once I realized there weren't as many flatworms in the tank I immediately did a massive water change and put a ridiculous amount of carbon in the display which ended up saving many of the corals.
I see the value in QT corals, but I don't really have the space. I dip 100% of corals as an alternative. I'll make sure my next house has room for this, though.
I wish I would have started out with a doser, it would have made things so much easier. That's all I would change.
And thanks! Took forever to save for the tank, but the dimensions are spot on.