Continuing the first thread while it was still on-topic... I tried Jazzware''s MIDI sequencer but found it really hard to use. Then again, it''s open source so it''s improving all the time as people add stuff to it.

I too use ModPlug Tracker for a large majority of my composition, it really is just another tool with its own freedoms and limitations. Only lately, as I have been drawn into more orchestral and "genuine" sounding music have I opted for higher end sequencers/samplers, purely for the soundfonts they are designed to handle and the manner in which they do so, but when it come to percussion and anything else that requires a smaller set of samples, it''s back to MPT!
Really it comes down to three things: The quality of your samples, your understanding of the functions built into MPT, and your skill at post production. It''s not just for demos any more