Bottle/Nipple speeds

If you exclusively pump, do you still pace feed your baby and use a slow flow nipple? What type of nipple do you use, and how long do feeds take? We are using Dr. Brown's level one and It can take 15 minutes to 30 minutes for a feed depending on how long burps take. We occasionally nurse just as a bonus but it's not really part of our routine. So I don't know if it's worth it to stick with pace feeding and the slow flow nipple or not.