Yeah, I read elsewhere that someone had been replanting the bulbs of shallots grown from seed for a number of years and they performed like a regular shallot, dividing. If they put up a seed stalk the advice is to clip it to push them into the 'divide and conquer' cycle.
All of the hybrid from-seed shallots appear to be shallot X onion hybrids. So there is more uncertainty when growing out the seed of a possible hybrid, as I'm doing, than there is from replanting hybrid bulbs. But as Alex says, that's what makes gardening fun.