I haven't really had much issue with customizing my wife's intercept. I tend not to run ROM but we have squealjoy's kernel and I use root explorer to remove the sprint apps stuff. We use Launcher Pro Plus. It works fairly well. She does get a slow down occasionally. I plan on getting her apps2sd working next and then maybe that will free up some phone memory to let in run better.
Samsung Epic EB13 Deodexed with Genocide Kernel
Samsung Moment DL05 Froyo Port Rooted with MRWRX Kernel 2.0.1 Recovery 3.1.1 and UD4.1
Samsung Intercept (Sprintercept) 2.2
For all your rooting needs. http://www.sdx-developers.com/