I have noticed that the 'bottom' of the cylinder is not joined, i.e. imagine a sheet of paper bent and joined to form a cylinder, the two edges of the join have their own vertexes but in a Blitz cylinder the tris share vertexes.
You sure? As far as I'm aware, blitz cycliners (and spheres, cones) have a 'seam' where duplicate verts are used - they're needed to UV map it correctly.