Damn... that cello is just not replicable with MIDI. Such a shame really that MIDI strings can't express solo strings.
The piano needs some humanisation. What I do when I'm sequencing piano, is i remove snap to grid and re-align every note individually so that it's not exactly perfect, or you can randomise note start values automatically. Do this to velocity as well, and even automating the sustain pedal and tempo will give you a more realistic sound... the actual piano sample isn't the most important element in a realistic sounding piano.
God I wish I could play the cello! haha. Great work
Also, I like to split my piano into groups in order to mix a better sound. This allows me greater control when cutting out particularly resonant frequencies in the low-mids.