I want to try switching over to pellets too - and I think they do sell pellets of grower (something between chick starter and layer) - but I'm nervous about buying a whole bag in case my 4 pullets decide they won't eat them. I wish I could easily buy a few lbs of them to try them out, start by mixing them in, etc.... My girls are only 14 weeks.
The crumbles are basically pellets that have been crushed into smaller pieces. I used crumbles at first, but found the chickens wasted quite a bit of food by scratching it out into the run floor. They don't tend to do that as much with the pellets. I sometimes buy a bag of crumbles if the feed store I use is out of the pellets, and mix it with what I have on hand.
They recommend that you switch to the layer feed when they are around 18 weeks or so, regardless of whether they are laying or not.
They need the calcium in order to lay eggs properly and have the hard shells.
It doesn't matter if its layer pellets or layer crumbles.
Obviously if you still have a bag left over when they hit 18 weeks you would continue to use it up and then switch.
I bought the layer pellets and one of my flocks hated them and wouldn't eat them and the other flock was fine with them.
I never bought them again, I like the layer crumbles better.
Both flocks will eat them, and I have no waste at all.
Mine never scratch them out of their feeder, if they did maybe I would feel differently.
Another reason I like the layer crumbles is that they pull double duty and can be used for hot mash on those cold mornings.
I don't know about crushing up the pellets, I mean if you wanted to spend a while smashing them with a hammer or something I guess you could, but it doesn't guarantee that they will eat them even then.
While both the pellets and the crumbles have the same nutritional requirements, they may taste different. They are a different color and the pellets may have something added to mold their shape. Maybe, maybe not just wondering.