All else being equal the bigger and slower prop will do better for climbing. But at the same time your motor is rated at a whopping 470 watts maximum output. That is WAYYYYYY more than you require for your Spirit to do well. So yeah, proping it with a finer pitch 9 to 10 inch folding prop and matching it with a battery pack which only lightly loads down to around a 200 to 250 watt performance level is going to make your new and lighter Spirit fly like a power model. At the same time your final flying weight will likely come out at anywhere from 10 to 14 oz lighter than it was before. And because your new flight power system is lighter take pains to pack all the heavy stuff as far forward as you can to reduce the amount of nose weight it will end up requiring.