I haven't pulled the trigger on an AP enclosure yet, but their reputation is second to none. I do have a Neodesha and a Boaphile enclosure (both purchased second hand) that I absolutely love. I've been a glass guy since I started out in this hobby almost 20 years ago. But these plastic/PVC enclosures are fantastic. I'm in the process of upgrading all of my enclosures gradually. AP is definitely at the top of the list.

As for the size, a T10 will be fine. I'd just wait until your BP hits 500 grams before moving him. But once he hits that size he should be ready to upsize.