Juan,
It depends on 2 things :
Size of Vehicle(s) and your height
With my Morris I can do everything without use of a step stool (!'m 5'11") but,
with my Chevy I need this - I bought one before Adam's had them but it appears to be similar but mine is not quite as nice. . I personally love it as i can move back and forth - I used a small one before and kept having to move it - now I dont have to do that.