I’ve finally put my argutas in the ground after letting them size up a little in containers for a few years. So far so good!
I’ve read of people letting a few “main” stems grow initially up because sometimes there is dieback. Is this a good idea? If so, do you remove all but one later when things get going better or just let them grow together? And if you let them continue to grow together does that mean you train multiple cordons together in the horizontal direction also? Seems like you’d get an even worse tangle then normal if you do that.
Still in the early stages, advice appreciated 
Planting:
When choosing a site for Hardy Kiwi it is important to avoid sites which have late spring frosts, as the foliage is frost sensitive. Hardy Kiwis are not heavy feeders, but an application of compost or well-rotted manure to the hole when planting would be beneficial. Do not allow the roots to dry out during the establishmnet year. Mulching around the plants will help to keep the soil from drying out. Plant Hardy Kiwis 4-5 feet apart. Since Kiwis are a very vigorous vine and can grow to 10 feet tall, they will require the support of a trellis or fence. When the Kiwi is planted, prune the stem back to 2 buds. Once these buds develop into shoots choose the larger of the two to be the main trunk and remove all others. Train this main trunk up onto the support by tying it to a stake or a wire. Do not allow it to twine around or this will cause problems as the vine gets older.
Growing:
Once the main trunk has reached the desired height, nip off the growing tip. From the shoots that will begin to form, choose 2-4 shoots to serve as the main branches and remove all others. Now that you have established the shape of the plant, future pruning will be to help ensure proper fruit set. This pruning should be done in the spring before the buds begin to grow. Hardy Kiwis mostly set fruit on wood that was produced the previous year. Remove any wood that was produced the previous year. Remove any wood that fruited the previous year and any damaged canes. Leave well spaced (10-15 inches apart) 1 year old canes. Prune these canes back and you should be removing 60 to 70% of the canes.