3000-3200 shouldnt affect engine life much, in any at all. the newer 24valves turn that much.
The springs purpose is not just to allow you to rev to 3200 or whatever, but to not defuel at the 26-2700 rpm range. It allows full fuel to and past 3000. the 4k is the same, just higher.
Oh yeah, the 4k does require the springs, as mentioned.
--Jeff