I was thinking about this issue.. There are some interesting points.. Firstly, its only one train-set on first delivery, secondly, I've done a number of fly-bys on the new barns at Wilson yard, and though they have usually some T1s parked inside, it seems unfinished. There is a lot of track-work to the north of the new barns that is yet to be completed. Also, if the trains are to be thoroughly tested, storing them on the Sheppard line's significant western tail-track, or even the rarely used and wholly unnecessary northern platform makes a lot of sense. Not only is this line a good test-bed (*remember its also been fully fitted with the new ATO-ready signaling system*), it will keep the trains completely away from the elements until the new barn is actually ready.
I'll head up to Sheppard today and see if I can see anything,,