I'd think it is definitely a go from e92 to E60 (especially an M) if financial situation allows; however, why a '06 or '07 model? The e60 m5 chassis is designed for smg transmission but models from these two years tend to have hydraulic pump and actuator problems. Manual did come out in 08, but the car just wasn't designed for this tranny, so I'd recommend going with an 08 if you can, and if you're lucky, you can find one that is still under extended warranty
