I see your 2 examples do not have the last row of canes at the very bottom.
One does, one does not. But, in fact, in our weights the last row is not a true row but the final part of the "between spokes" canes. Some of the variations in the general pattern were achieved by using smaller and larger canes such that between each spoke, counting from the inside to the outside, there could be "1-1", "1-1-1", "1-2", "1-1-2" groups of canes. Some larger (3 inch +) weights could have a "1-2-3" grouping between the spokes. And some could squash even more canes in!
Would that help in narrowing the date of the piece?
Unfortunately, the number of canes between spokes does not help to specify a date.
... the 2 samples you list seem to have a solid blue color on the bottom. Mine has a spotted effect.
I think that the vast majority of Strathearn (and earlier Vasart) weights with a coloured ground had a solid colour. But yes, "spotted", or "mottled" ground examples do turn up and yours is a good example of the type. I am not aware of whether that might be a clue to dating, or just an "accident of making" at the time.