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You could run say a 160mm blade if its specced for a 165mm, but it would affect your depth marker so not ideal. I would personally stick to the size its specced for. Bear in mind you'll likely have to shift your splinter guard if you change blade types as the kerf will be slightly different. Also if the saw has a riving knife, obviously don't go thicker. Makita use thinner kerf blades than most of the other brands which leads to a faster/easier cut, but I would have thought at the expense of more blade deflection.
Assume you mean 250 vs 254. Nope, other than you will lose 2mm of cut capacity. The 24T from that set is the one I have, I think you will be happy with it / them.
FYI, Freud have updated their line and those blades are now superseeded by these:https://www.ffx.co.uk/product/Get/Freud-Fr23W001T-4059952521732-250Mm-X-30Mm-X-T24-T40-Table-Saw-Blades-2Pk
I don't know if they have gotten better or worse, the anti vibration slots look more contemporary...