We have both in our playroom but until very recently we had four Trofast smaller units set up to be a train table (a HUGE train table). I always thought that when the kids outgrew the train table it'd be great that we could repurpose the Trofasts into something else and we did. We stacked them up two sets of two and now they're just storage areas. I don't mind them and can't say that I prefer one over the other (Expedit vs. Trofast--we have the 5 x 5 Expedit too).
We have different sizes of bins and they've worked well. When it was a train table though we often had kids pull out the bins and hide in the middle!
ETA: A picture of when there was a train table: http://www.facebook.com/media/set/?s...27949f6&type=1