For what it's worth here are my experiences of Hemp growing here in Canada having grown 160 acres this year for seed.
Here, you have to have a licence from some nice French lady in Quebec from some govt. quango along with police quecks before you can grow, sell and store hemp.
Seed is expensive and no sprays are available so you need a clean seedbed and good establishment, so once started this crop is a fantastic competitor, but does not like wet feet.
Combining can be a problem as it raps arround any shaft it can and so will destroy bearings or go on fire, and if very dry the dust can gather and also burn. So preparation of combine is a must, cover all exposed shafts.
4 growers in this area all had completely differing problems, feeder house chain feeds, rapping arround thrashers, and destroying wobble boxes.
I just cut the seed heads off with the header as high as it would go and got the seed into air bins as soon as possible. It doesn't ripen evenly so shelling will happen and some green will need attention.
We then swathed the straw (swather now needs repair) and round baled.
Real problems... marketing, the buyers that contracted to you at planting are bust by harvest, no market for the straw as the plant that was being built doesn't exist and the stuble is just a bed of twine that will be a b... to zerotill.
Will I grow it again? Doubt it unless we go through another period of poor crop prices for other grains and oilseeds, but a 1000lbs/acre of seed here in Canada is achievable at $80/lb and nothing can match that on my farm.