The XC's are really based on the SX models for the guys who race WORCS and such and don't want to go to the time and expense of trying to convert an MX bike to offroad. Thus, they have stiffer suspension, close ratio transmission, more aggressive ignition, billet triple clamps w/adjustable offset, etc.
The XC-Ws have the wide ratio tranny (hence the W) and plusher suspension. As you pointed out, for '08 they'll have e-start. Even though the '08 XC-W is supposed to weight the same or less than the '07 XC-W w/o e-start, I'm like you in that I don't want yet another battery and the weight. Even my old KTM 300 is a 1-2 kick affair, so this alone will push me to an XC.
The other thing to consider is there are some great deals on the '07s now, which were all new for '06 and were really dialed in for '07. That said, I believe the new shock design with the longer spring is going to be better, especially coupled with the new stiffer frame.