I have no experience with the marshall, but I hear that the entire marshall MG series just absolutely sucks! I'm not familiar with how a fender frontman sounds, but if it sounds anything like how my fender fm212R sounded, then you can achieve a similar sound with the line 6. the line 6 can get a good rock sound if you take the crunch channel and crank the gain high, and a good lead sound by taking the insane channel with a moderate-high amount of gain, however trying to play rythm with the insane channel is muddy. the metal channel sounds ok with with low amounts of gain, but crank it high and it's horrible. and the line 6 has a reverb and a tape echo effect. so, I'd say you're better off with the line 6. it's not horrible, but it's not professional sounding (though, what amp in this price range IS professional sounding?)