Ironically... I posted on this thread previously. I now have personal experience!
I have a 10g QT, running a Biowheel 100 - just like the original poster. The only difference is that the Biowheel wasn't seeded from my main, but I'd cycled the QT previously. It'd been about a month since there'd been a fish in it, but I'd been "feeding" it with food to keep the bacteria levels up.
10 days ago, I bought three chromis and put in the 10g QT - just like the original poster! The next day, ammonia readings were at 0.25ppm. Surprised, I did a 50% water change, and added a bag Purigen to filter. Each evening, I was getting 0.25-0.50ppm ammonia readings, so I'd do a 50% water change. After 3 days of this, I put about 2 cups of sand from my main into a mesh bag, and put that in my QT. Ammonia levels didn't drop. In a nutshell, I did 50% water changes for 7 days. On the eighth day, my ammonia finally disappeared. I've now gone two days without doing any water changes, and have 0 ammonia and 0 nitrites. Phew...
All through this, the fish have seemed healthy and happy, eating like pigs. They're really nice colored fish, so I didn't want to lose them, so I was scrambling to try and keep the ammonia levels down.
The funny thing is that when I first had the ammonia spike, I searched the forum looking for advice. I found this post. With my own comments.
I guess I'll have to revise my comments: with 3 chromis (3/4 to 1" or so) in a 10g qt with a Biowheel100, you might see a little ammonia spike before things "catch up". I was afraid I'd never catch up and end up doing 5g water changes for a month! Luckily, things finally settled down and everyone seems happy.
(And yes... I've also learned that a 10g QT is on the small side. I remember a few folks tried to tell me that when I was first starting out.