Don't understand why, from a owners perspective, getting a Y with standard construction, 2 piece sub frame or 1 piece cast piece will effect your ownership experience.
Same with the announcement of future battery improvements, taking battery production in house, million mile batteries, smaller electrodes, different chemistry, Maxwell technology etc. Car driving experience will remain relatively the same.
Of course, everybody wants the latest and greatest, but no matter when you buy a Tesla, something better is most always just around the corner.
On another tack, no reason not to delay your delivery just a few weeks if it makes you feel more comfortable, and you are willing to get into the back of the line again.