Forget about the 50 watt idea. Why own a 50 watt head when you can own a 100 watt and turn the volume down 1 notch? The volume differential is very minor, but the headroom is greatly improved.
Also, attenuators are cool if you need to knock it down a bit. The Weber Mass 150 I sold was great. The only reason I got rid of it is because when I want the cranked amp tone, I keep turning the volume knob