You should only be stick feeding H. erectus if you had wild caught seahorses. Most seahorses in stores (though not all, there have been a glut of wild H. erectus popping up all over) eat frozen mysis shrimp because they're tank raised. They are much easier that dwarves. However, I'd look for true captive bred seahorses over tank raised, which have their own problems.
I don't want to post a link here being a newbie to the site, but I've written about how to pick the right seahorse. The short version is; don't get your seahorses from the fish store, they sell them too young and rarely in good shape. Seahorses from a breeder, though more expensive (shipping) tend to be much healthier. Fish store "kudas" can be any number of species and are probably sickly and underfed.
You're really going to want a minimum of a 30 gallon for any species besides dwarf seahorses. Don't let fish stores tell you otherwise - they frequently sell the tiny babies saying nanos are okay, and unfortunately it just can't support the growing seahorses, so they die. You can start them in a small aquarium (it sometimes helps for concentrating food) like a 10 or 15 gallon. But they grow fast, so you pretty much have to start the other tank as soon as the first is done cycling.
I don't mind the extra work of hatching brine shrimp because I do it anyway. But unless you're like me and have it brewing for other critters, you'll probably get tired of hatching brine shrimp sooner or later.