I've bought from them many times over the years and they have always been on the level.
For the "birds beak" I also like to drill a 15 or 20mm hole at the apex of the cut. This gives you so wiggle room to work the saw.
I also taper it from the edge of the hole down to the front edge, the taper is the full width of the block and the angled side (chamfer?) is on top. This allows you to work braced at different points with different thicknesses of jobs and awkward shaped jobs. It is especially helpful when filing and shaping an object.
BTW Gav, do Stewmac really sell bunches of 10 saw blades? It is more usual for it to be 12 blades.