Well, two very different experiences.
All I can say is that I enjoyed showing in Juniors. I worked very hard, and put a lot of effort into learning about showing, training, and grooming. Sometimes I won and sometimes I lost, and sometimes I felt like I should have placed higher than I did, but that's part of the learning experience.
In the end, it really doesn't matter who beat me, or who I beat, or who had the fancypants-top-winning dog to show in juniors, because we've all moved on to bigger and better things. Many of the Sheltie kids who I competed against in juniors are now starting successful handling careers and breeding programs. Some of them (like me) are more casually involved in dogs. In any case, for me at least, with time and age and perspective, the wins and losses don't matter nearly as much as the time I spent with Mark, the values I learned, and the friends I made.
You mileage may vary. As I recall, your daughter is already involved in 4-H, which is another fantastic program. Having Jake will give her the opportunity to try both 4-H and Juniors, and to figure out which she would rather focus on - which is a great opportunity in itself.