If you can keep track, then go for the 4 needles. Also, if you want, and this is backed by EZ and Amy, you can use a fifth needle of a one-size difference for the fifth. Those stitches will be scattered throughout the pattern, so you wouldn’t have one strip of larger/smaller knitting.
I’m using 3.5s, so using a 4 wouldn’t really be that big a difference, anyway, right?
I think I might try the four dpns and see how well I can keep track before getting the 4s. I’ve already made a sock–well, let’s just say something that has “sockness”–and keeping up with needles 1, 2, & 3 wasn’t hard at all. My problems were elsewhere…
I think it depends on where the decreases are. I tried making a mitten (I know not the same but that’s all I got) with 4 instead of 5 but the decreases made a triangle shape with five and wouldn’t work with four.