My 10yo is using Rakza 7 (on a 5ply) and had zero problems adjusting to it after the slow, thin, dead 729 non-tackies that were on there before. Took her less than one training session to get the balls where she wanted them.
My 7yo has hit a few balls every now and then and I honestly see zero difference between him using his sister's bat, or one of the club's older battered ones with deader, slower rubber on it. However, with a premade, it's both harder to feel what you're doing, and less potential to handle the ball with.
Premades are 99% of the time either:
- " Carbon" in such a way that there's zero feeling, just a maximal sweet spot. Which is great for fun because if you manage to hit the ball, it will go to the other side.
- Crap quality wood in such a way that the results are plainly inconsistent
- Rubber that's made to last -> hard, tough, and doesn't really do much in terms of spin or feeling
- Rubber that's made to be cheap -> quick to degrade, some even have the feeling of being plastic right out of the box
Point being, a custom bat with at least slightly sensible choice of materials isn't "too much" for young kids to start with. It's hard to go over that limit if you stick to medium properties. At the same time, the potential of said bat is much, much higher, as well as the lifetime (of the blade, but arguably most medium rubbers too). I expect my daughter to have a good time training with this bat for 1,5y easily, maybe 2y before she needs a rubber change. If she's developed a good bit by then we might need to step up, but we'll see.
Now, the blade is 25-30 euros new (I got it second hand for much less) and the rubbers are ones I used for a few months. The investment cost is really not that high.