RAMPS for Rostock?

I've just completed printing out the parts for a Rostock and am now sourcing the electronics and other vitamins. When I go to purchase a RAMPS 1.4 board, I see that I have an option for 4 or 5 steppers. The Rostock uses only 4 steppers. Prusa's and others like it use 5 steppers. Is it going to cause any issues if I buy the board ready for 5 steppers but use only 4 for the Rostock? Will this cause me to have to change things in the firmware or software? The reason I'm considering getting the 5 stepper board is in case I decide to build a Mendel90 and swap out the PSU and RAMPS board to run that at times.

Technically, the RAMPS 1.4 has pins for 6 steppers - one for x and y, two for z (same stepper driver ) and two extruders.

I'm pretty sure there is no problem leaving the second extruder empty.

You'll be fine. I'm running my rostock off of a Ramps 1.4 with 2 sets of pins for z axis.

Great. Thanks!