The mount isn't compatible between Canon and Nikon without an adapter, you shouldn't go down that road unless you decide to completely switch over one day. What I was saying like canon works with any canon gear, Nikon works with most nikon gear.

Renting is an excellent option to test it out before you buy if you are not sure before making the commitment to buy. Yes always keep your upgrade in mind when buying lenses, it saves on cost. By now I have over half dozen lenses, would be expensive to have to buy all that again at once in new technology! Reuse what I can first.