I`ve changed lately from 70 mm to 115 mm, and the handling was what i expected; BETTER
With my old shock the riders weight was pretty much on the front, the handling on downhills was terrible.
The geometry changed with the new shock, and the weight is more on the back now, wich improves handling on high speed decents.
And yes, the climbing skills are worse than before, but i can take that
I think you will notice some difference, but not so radical as you thought.