Brian - I'm not sure about this Davids Rd Wharf.
There must have been some sort of wharf near the dartmouth arms, but it is not marked on the maps.
As discussed here before, the havelock walk studios were mostly stables not warehouses - and in any case were built after the canal had closed.
I'm sure someone will correct me if I've got this wrong.

But sure, it is well established that the canal went along what is now Davids Road.

If you ever get to stand at the back of Dacres Rd reserve, you'll see why the canal had to deviate from its course - Pigs (peak) hill is a significant obstacle.
An obstacle the canal diggers had to work around, while the railway builders had the money and manpower (and machinery?) to cut straight through.

So the site is not only an attractive nature reserve, it is important historically too. I think we can all agree it should be be regularly open to the public.