Good question about Splake. I thought about it as I replied previously. As a hybrid, splake obviously aren't a native species, but they are a hybrid of 2 native species (which you know) - brook trout and lake trout. They also are not able to reproduce in the wild because of the mixed up spawning schedules of brook trout and lake trout.
As a put-and-take stocking option to support heavier fishing pressure in lakes that can't support a self sustaining native trout population, I think that splake are good option. That includes the lake my cottage is on (outside the park) and especially lakes where water levels fluctuate radically like anywhere that supplies the Trent-Severn. Splake have the benefit of growing faster than lake trout and while still doing better in lakes that are less suited to brook trout.
I'm Ok with splake being stocked in Algonquin lakes, especially lakes facing high angling pressure, but a case could certainly be made that only native brookies and lake trout with the potential to reproduce in the wild should be stocked in Algonquin.
Closer to home, I would also like to see the Brown Trout stocking on the Grand River phased out and support given to supporting the recovery of Brook Trout, which are still present in creeks feeding into the Grand.