ladykirvin,
well i lugged around the PISA wherever I went for my #1. in the end I didn't use the backpack, it was like a dead giveaway that "look at me i'm breastfeeding" so a bit vain lah i carried around 2 soft 'boxes' - the pump which was quite heavy, the ice pack which was just as heavy but i squished the medela bottle, cups and tubes all into the ice pack cooler! I had a bulky bag.
in the end because my flow was not that much anymore I switch to carrying the avent manual breast pump (SGD90 i think), which works really well as a manual pump, but can only do 1 side at a time. it also makes a horrible "squach-squach" sound which sometimes leaves people guessing what's going on in the toilet cubicle. but hey, 90 bucks, works, and super light! i will probably stick to the same configuration this time round. but the freestyle pump looks really cute and not so boxy so will probably be more inclined to really maximize its use.