Mike has a Canon 20D with three lenses, and was either looking at a Canon 7D to keep the same lenses or get the Canon 5D and get new lenses. Leo says he could keep his lenses with the 5D, but there would just be a crop factor to it. If he's considering getting all new lenses, it may be time to go mirrorless with the Sony A7S.
Mirrorless cameras are smaller, lighter, and they're really the best cameras out right now. The only downside is that with mirrorless, he'll have a video feed into the viewfinder. Leo really likes it, though. And the full frame of the A7S is fantastic -- it works just like an SLR.