Personally I have a ramp that goes into the hutch for my rabbits, and neither one of them use it at all. If your guy is getting up and down alright, then I wouldn't think it's necessary, but I suppose if you tried it out, it wouldn't hurt.
Maybe you could use the spare piece to create another small level on the other side of his cage, or cut it in half and join the two pieces together in a point like this, / \ for him to use as a hideaway?
Sorry - I should add that to me, the ramp does look a bit steep.
Best of luck!