In this a little late but here's my two cents.
All lifters should bend the back leg somewhat at the knee. If you keep that leg straight, it will invariably draw the hips "out the back" and eliminate the correct support for the bar above, which should be a column of bar-shoulders-hips supported by a pyramid of bracing front and back legs. You will end up taller with the bar forward.
I will add that I never teach lifters how far they should be trying to get their front leg or back leg out but emphasize getting both feet back to the platform as quickly as possible, in proper relationship, after the proper drive in the jerk has been accomplished. I think training individuals to step through with the front foot or drive back with the rear foot ends up actually taking away from the drive portion of the Jerk, which is critical.
Also, remember that the back leg should be bent at the knee (slightly for most) and the foot should be dorsi-flexed and the forefoot grounded. The front leg should be bent more at the knee, causing the shin to be vertical and the front foot should be turned in slightly. The lifter shoud concentrate on putting his front heel down, rather than the forefoot, as the latter can often lead to the knee ending up too far foward.
And, of course, the final position of the feet should not be any closer to the front-back midline than they started.
The split, in my opinion should not be thought of as steps but putting legs in a bracing position supporting the torso and bar above.