My tomatoes seem to do just fine, but I've heard they might do even better if I pruned them. If you prune a determinate variety incorrectly, it will stop growing and so should your expectations of a bountiful harvest from that plant.
Vine tomatoes, however, normally respond positively to pruning.
Be sure to drive your wood or metal stake firmly into the soil about 1 foot deep and about 6 inches from the stem. Continue to shape the plant throughout the growing season. If you grow your vine tomatoes inside a wire cage, you'll only need to prune once and you can leave more stems. Maas suggests three or four. My family does a lot of barbecuing in the summer when the weather gets nice.