> All people I know who use them, just run them once before a race to try them out and after that they are like a very good suit which you only use for special events.
Doing all your marathon training in one type of shoe then switching to a different, new shoe on the day is certainly a choice.
There are usually training versions of the race shoe, which are heavier due in part to thicker rubber soles and more durable foam. So you train in those, and then switch to the ultra-light, ultra-bouncy race version on race day.
Doing all your marathon training in one type of shoe then switching to a different, new shoe on the day is certainly a choice.