Sowing for Autumn/Winter Harvests

I mainly eat stored food over winter: dried beans, potatoes, onions,tomatoes, garlic, soft fruit, pumpkin, squash, peas, apples hopefully till January. Then still from the garden/polytunnel: beetroot, carrot, cabbage, kale and leeks. 

The only thing I sow about now is Senshyu Yellow onion seeds. I used to grow sets but find seeds are far cheaper and the onions end up the same size. £1.19 + postage and there should be enough seeds for the next 2 years hopefully. I do tend to lose a good percentage of what I plant out but still end up with over 50 reasonable onions. I usually just leave the seedlings in a seed tray and they do look very vulnerable when I plant them out. This year I've put then in root trainers and hopefully they will be a bit sturdier and not have so much root disturbance when planted out.

How does Senshyu store for you? I've always been put off because of its apparently short storage life. Toughball F1 and Hi-Keeper F1 are my overwintering onions this year. Toughball stores really well, this is the first time I'm trying Hi-Keeper. Hopefully 3/4 of them won't get killed by vine weevil larvae over winter this time!