Sample content on external HD (USB 3.0)?

I’m thinking about moving my sample libaries (1.5 TB total in size) from two (3,5’‘) 1 TB - HDDs (one running on the “old” SATA II bus, the other one with eSATA, also version II) to a mobile, external (2,5’') 2 TB - HDD connected via USB 3.0.

I wonder if loading speeds will stay the same, improve or even change for the worse?

Can anyone guess if there will be remarkable differences in whatever direction?

Oh, and the old HDDs have 7200 rpm of course and the new one will probably have only 5400… as almost all 2.5’’ HDDs have, as far as I can see. :cry:

And apart from the speed, might there be other drawbacks I haven’t thought of when considering working with an external HDD?