i have never heard of anything being bad about behringer... you should atleast say why you think it sucks.and he wouldnt need MIDI for mashups, unless he is creating his own loops with a synth or something of the likes.
also, most computers won't have a sound card that is good enough to process sound quality from a good synth or MIDI instrument and be able to mix it down into an MP3 or wav. file.
I am running a Yamaha S-90 synth into my laptop and im using CuBase LE. but i cant do an audio mixdown till i get an external soundcard like the Yamaha Audiogram 6 ot 3.
i dont know how much different it is with mashups compared to creating your own stuff from scratch, but do your research and make sure you arent throwing your money away on rediculous things that wont work.