I've always preferred primes, I always end up buying whatever the 'pro' zoom is for whatever system, and I use it for a while, love it, then kinda get bored of it and lust after primes again. When I shot Nikon I ended up with the usual suspects, the 24-70 and 70-200 2.8, I didn't take to either, could count on one hand the amount of shots I really liked with the 70-200 in particular - but I found the 24-70 just clunky and too massive for what it offered. The Oly 12-40 is much more of a pleasure to use, it's 1/3rd the weight for starters and every bit as sharp, has slightly better magnification and much better MF implementation - but .... I kinda miss primes. Thinking the Pany 25 1.7 and this Sigma 56 1.4 would be the ideal pairing for me ... but I'm not jumping at it just yet. The 12-40 isn't one you let go of so easy - if I can swing it I'll keep it and get the 56 a little later, be real nice for late Spring/summer
And I know I'm a fussy tw@t when it comes to FL, I detest crossing over, which is why I wouldn't keep a 25 owning the 12-40. I just see it as waste when I could have something different. With the zoom though, I almost always find myself zooming in to about the 25 mark anyway, so is it a waste? I must keep check and see how often I actually use the wide end, and at what aperture. Because if it's rarely, and stopped down, a cheap kit lens would suffice for those occasions