I'll vouch for steeping grains adding a lot. I moved to partial mash early on as well, then quickly got away from kits and into making up partial mash recipes. I was using the partial mash to get everything I needed and the rest I made up with light DME or sometimes added some Amber DME to boost the Crystal/Caramel content a little more.
The neat thing is, it's easy to start partial mashing. Get a bigger bag for the grain, add the steeping grains from a kit and a pound or two of a crushed base malt like 2-row, 6-row, Maris Otter, etc. "Steep" for 45-60 minutes and you've just partial mashed. Granted, the gravity boost is going to be minimal from a small mash like that, but it's a way to get used to the process. Just make sure it stays under 170* for the "steep."