I know from personal experience my lifters ended up being collapsed. I say replace them while you have everything apart. No use having to tear everything apart again. You'll have the old one's out anyway.
How many miles on the stock lifters? I agree with the others. Not a "must" but unless your budget is running thin you might as well. I didn't change my lifters when the cam went in and I got another 100k+ out of them before having any problems. Pretty annoying having to remove the intake (among other things) because of one bad lifter. Then again, I got a total of 280k hard miles out of them so I shouldn't complain.