OK, this thread is probably dead, but I feel compelled to leave my 2cents: I don't know if anyone keeps official track of how many people go missing on EBC, but I doubt that it's more than a few a year (I spent over 3 weeks doing the 3 passes trek recently and don't recall seeing a single missing person sign at the teahouses). But it's irrelevant - regardless of whether a few dozen or a few hundred have gone missing over the last 20 years, the biggest risk by far is the flight in (if you are flying into Lukla, something almost all guided groups will do).
A plane load of tourists perish every few years coming into Lukla due to the notoriously unsafe airlines and complete lack of modern equipment at the airport (it's hard to imagine they get by w/o a radar at Lukla). Lukla has been labeled one of the world's worst airports, and for good reason.
So not to scare anyone interested in doing the trek, but do note that you're kinda splitting hairs when you start talking about going missing on the trail.
Anyways, whether you're deciding whether to go solo or guided, do it because you value what each option provides, not because you're afraid something will go wrong with one or the other. And do note that guided trips have their own risks - being on a rigid schedule means you might be forced to acclimate faster than your body wants, have to hike while you have the squirts, lose out on sights because the team schedule conflicts with bad weather, etc.
And, as much as I love my solo trekking, the Nepalese need your guided tour money - if you can afford it, that extra $3000 will go a long ways towards improving the lives of everyone involved in your trip. Just make sure your money is going to a local company, not to a US/UK-based entity running the trek...