Currently I have an EM1 and the Panasonic 14mm as well as the Olympus 25mm, 45mm and 75mm lenses. As you can tell I love me a fast lens (I wish sigma would make a 1.8 zoom for M43 but alas they probably don't think there is enough demand to justify or pay for the research)! I love my primes, but sometimes I have missed shots because I've had to be changing lenses. Reviewing my shots I find I use the 25mm the most followed by the 45mm for most portraits I do then the 14mm and lastly the 75mm. I love the 75mm and I know it's one of the best lenses out there for the system but I don't usually get the opportunity to use it as many portraits indoors and even outdoors don't allow for the needed distance to use the 75mm. So while it may be better than the 45mm I use the 45mm more because of the focal length. I have used the 75mm when photographing performers from side stage and especially at night it can't be beat! Below is an image I took from side stage without needing to do much cropping at all: 75mm But below you can see the benefits of the 45mm as in this setting I didn't have much room to work with when photographing my daughter the day she was born. 45mm The 25mm is a great all rounder, can do portraits and everyday shooting which is why it's usually on my camera, and the 14 is for whenever I need something wider. 25mm 25mm But before I go on and on about my lenses, let me get to the point. I think I want/need to get the 12-40 pro lens as it would be very convenient vs all my primes and my girlfriend friends can stop asking me "how do you zoom?!" when I give them the camera to take a pic of me lol. My issue is I know I will be able to get rid of the 14mm as it will be redundant (except for it's convenient size!), but it's so hard to think of parting with any of the other primes. Practicality says get rid of the 45mm as it's close to the 12-40 though not as fast, and I have the 75mm which can do portraits and will make my kit more versatile. But another part of me is saying I hardly use the 75mm so get rid of that and the 14mm and keep everything else, but so much range will overlap that it really doesn't make sense. Please give me your advice and help me decide which direction to go in, and if anyone wants to part ways with their 12-40 I'll snap it up as well lol.