To the OP, will a sub compact load and move #4's? Yes it will, my 1025R has moved everything from fine pea gravel ( #9's ) to rip rap, moved rocks that were as big as the bucket and dug holes the tractor could have been buried in all without a toothbar. The only damage to the bucket was paint, not bent, not dented, not twisted and certainly not broken.
When people tell you the loader will not dig, they simply are wrong. Some loaders are designed better than others and therefore dig easier but the point is a loader is built to dig. After a lifetime of operating construction and mining equipment I will tell you it is not a matter of brute force but a matter of knowing HOW to effectively to use the machine you have.