If I had a 2nd, back-up, older sewing machine I rarely used - sure! No problem. But like I tell my kids, if you allow someone else to use something, it probably won't be returned in the same condition. So make sure you're prepared for that fact!
That said, there's no way I'd loan out my new Pfaff! I'd let her come over some afternoon and help her with her project in my home, though.