10gbe or 2.5gbe dongle

I am considering adding 10gbe, which is +$90 to the base price.
My current use case I'd only really need 2.5gbe, and adapters are very cheap.

plus side of getting it in the mini is that it's one less thing hanging off the side of it.

not sure if there is any benefit speed wise -- there are plenty of thunderbolt ports which should be able to accomodate the cheap dongle for 2.5 or a 10gbe one down the line