If we were all like gerbils, we wouldn't be able to live properly. Not to mention the fact that you would be growing an inch every day. Life would be too short.
However, with a tortoise's lifespan, we would be able to accomplish more, work more (Unfortunately, more school), and just do more in our first five years.
I think I would stick with my lifespan right now, until they find a way to implant our minds into computers.