I suppose it matters where and when in the spring you are going to be. I can say with some confidence that in the North Cascades come say, April 1st, you'd want them!
But honestly, if you are a north bounder leaving aruond the end of April, it's still too early to say where and if you will need microspikes, crampons or snowshoes. Ok, likely you could go wihtout snowshoes. Last couple of years were big snow years. In 2009, it wasn't at all. Yeah, there was plenty of snow in the Sierra but I walked across it in nothing more than trail runners. Last year there was snow for much of the trail at higher elevations, and people used microspikes and crampons. But snowshoes? Probably not so much.
If you haven't checked it out, these questions are great to ask on the PCT List Serve. The link is http://mailman.backcountry.net/pipermail/pct-l/
Many experienced people are there and on top of it, these questions do come up and are discussed pretty much in depth, especially in the weeks leading up to the PCT Kickoff.