Brake Fluid in a modern master cylinder

I'm installing a modern Honda Fr brake master cylinder & new ss braided brake lines onto my 81 KZ650-CSR w stock caliper.
On the mc cap it says to use Dot 4 & I'm planning on using Dot 4. AFAIK, dot 3 & dot 4 can be mixed and dot 4 has a higher boiling point.
Other than the boiling point, is there some other reason why dot 3 shouldn't be used? Just wondering. Thanks.

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No reason 3 can't be used. Just as you state, 3 & 4 are compatible.