Soundbar v 5.1 (minus rears)

[cornershop]

Question folks .....

Will a decent soundbar with sub sound better than a 5.1 system with the rear's removed (3.1?)

I don't want cables running around the room, so my preference based on reviews and with approx £400 to spend, is the Yamaha YHT-S400. Second consideration is that my Panny G10 is placed in the corner of my lounge so maybe not ideal for a soundbar as I imagine the sweetspot is bang in-between the two seating positions.

This is also based on an assumption that 5.1 systems with wireless rears, still need access to mains power to work and therefore not completely wireless - is this correct?

Thanks in advance