Welcome to HBT!
There is a difference between steeping and partial mash. With steeping you are only getting color and flavors from the grains. With partial mash you are extracting the sugars as fermentables.
I have a brew buddy that doesn't have interest in AG but I have moved him to partial mash. Because he brews on his stove top, 3.5 gallons is about all he can handle for a boil. Just yesterday we did a PM with a 5 gallon Igloo cooler, a large paint strainer bag, and a good thermometer. We actually got a lot better efficiency that the recipe called for.
PM is definitely worth it! You get better tasting beer.
Here is a good read:
http://www.homebrewtalk.com/f39/easy-partial-mash-brewing-pics-75231/