The L4 is actually my go-to product, I wear them every day. The Preschools are a bit less absorbent, if you've ever tried the L3s, I'd say they're comparable to those. Whereas I would normally stay in a non-boosted L4 for 5-6 hours, the Preschool is probably more 3-4, and I'm completely incontinent. Also, this may or may not apply to you, but I would warn you that the landing strip does not extend as far out as other diapers, even other ABU diapers. I had a thread on it recently, and it was a problem for me. But as long as you're well within the size range, you should be fine, and the absorbency is fairly decent, if not quite on the level as Abena's premier product. If you're looking for that level of absorbency, the Space and Simples more than match up to it, I have some of the Simples on hand myself.
I would also repeat the mantra of getting a sample first. For the price, if you can fit in them, they're definitely one of the better products out there, just don't be expecting to stay in it quite as long as you would the M4 as a general rule.