I was looking over Suricata's ship tier chart, planning out my future advancement, and it seems to me based on the numbers available that nearly everyone would probably want to skip over the Recon Science Vessels and go straight for a Deepspace Science Vessel.
Recon and Deepspace are alternative ship types, i.e. you have double the amount of ship classes at T5. At T5, every ship type (TAC, ENG, SCI) has two sets of 3 classes, and the sets have slightly different stats and BO slots, so you can choose between slightly different base configurations to then customize upon.
In other words: In T5 there is twice the amount of ship classes to choose from.