My plan from the beginning was to go up without a guide but not solo. The question if one needs a guide to climb Elbrus is a good one and the answer depends on how one sees the role of a guide.
The standard route up to the summit of Elbrus from Barrels Huts is very straightforward and very well marked. Based on my experience only heavy snowfall or purposeful removal of the route poles can make it difficult to reach the summit without a guide. GPS with preset waypoints goes a long way to help even in those situations.
Up on the mountain on a bad weather and visibility there's not much to see. Most often the goal is just to get to the summit and back. On good weather there are several points of interest like the East Summit, the wreck of the Land Rover and the Saddle. A professional guide will probably be able to point these out and also give some background info making the experience more thorough.However, most of the information can be obtained beforehand in the net and GPS can point out the exact locations. In the end using a guide for this purpose is a trade off between convenience and the feeling of independent discovery.
What comes to accidents Elbrus is relatively accessible and well monitored mountain. Even in bad weather help is unlikely to be more than a couple of hours away if an emergency call (preferably by satellite phone although cell phone works in most parts of the mountain) is made. Also due to the general popularity of the mountain as a climbing destination one is seldom alone up there. Despite all of that accidents do happen and people die every year, mostly solo climbers or in unguided groups. Presence of a professional guide more or less reduces the risk of an accident and the guide is likely to be more efficient in coordinating first aid and evacuation. I do not, however, have any first hand experience of the competence of the guides up in the mountain.
My conclusion is that during high season (July - September) a professional guide for the sole purpose of showing the normal route up is not necessary. A climbing partner, however, with first aid skills and adequate means of communication is a damn good idea in every case.