as someone with both..
I admit I haven't read all 3 pages of this thread.
I vote i7 now and add an SSD later. Ordinarily I would downplay a CPU upgrade as that's rarely your bottleneck, but with hyperthreading enabled only in i7 and the considerably faster clock speed, it's really a different machine that'll last longer and have a greater resale value. SSD doesn't actually make your more efficient, it's really a luxury item for snappiness. Don't get me wrong, I love mine and won't go back, but it's something that can be added later, an i7 is not.