I rented this pump from the hospital when my baby was born at 33 weeks. I started pumping 20 minutes after he was born (vaginally) and I got 6 cc's of colostrum!
I used this every 2-3 hours for 12 weeks and I have this machine to thank that 1) I even established a supply and 2) that my son was able to start breastfeeding.
This machine was so efficient and effective for me. My son was 'too small' to breastfeed and then had nipple confusion, so he did not routinely nurse at the breast until 12 weeks (when a switch flipped and he just went to breastfeeding and we went to exclusively breastfeeding within 24 hours). However, despite this I was able to establish a supply with this machine. I didn't have an enormous supply and I didn't have a stash or anything, but I had *enough* and that's really all you need!
I had, also, a Medele Pump in Style through my insurance, but it wasn't as effective as the Symphony. My advice is that if you're building a supply for a preemie or any other baby who cannot breastfeed, you need to use a hospital grade pump like the Symphony. It makes all the difference.
Overall, if faced with exclusively pumping again I would certainly rent this pump again. I don't think anyone needs to BUY one, unless it's more economical for you (if you will need to EP for more than a year or something).