I've never seen the Marshall, but I have the Bose. It's great for what it is...a small pa that happens to have bluetooth. Battery power is a nice option, too.
As a small PA it's great. Acoustic guitar sounds better than most 'acoustic' amps i've tried, and the sound gets spread evenly everywhere, same with vocals. The fact that the 2 pa channels have bass, treble and reverb is a surprise for a Bose product.
As a bluetooth speaker I find it a bit harsh, lacking sweetness that most bluetooth speakers add. It works amazingly well for streaming background music outdoors...just stunning. But for nearfield listening it wouldn't be my first choice. There's no EQ on the bluetooth channel. I have a Sounddock 3, and that is much smoother and better balanced for streaming.
just my 2 cents