I'm not sure what Walrus means by no IFR in VMC at GAAPs. I've done a few practice NDB approaches and practice circle to land at YMMB when the circuit wasn't busy. No probs at all with tower approval.. and as Krusty says, you're asked to just follow the traffic pattern as you would if you're flying VFR. I even recall a few years ago that YMMB had standard IFR departures in the DAPs.
As for how the new changes will affect IFR training at MB, that would be interesting. What happens during a practice NDB approach, when you call the tower after turning inbound, only to hear the circuit is full? Cancel IFR and track to a VFR approach point and join the queue?