My reasoning for giving this any consideration is twofold--to kick up my photographic skill a notch and because quality zooms are heavy. I have tendonitis in my right hand that flares up every once in a while, so weight matters.
What got me to thinking about this is that I'm looking to add a second body to the bag, most likely a K2000 when it comes out. If I've got primes attached to both bodies, then neither weight or lack of flexibility will be a big concern. Since the K2000 does come with a kit lens, I would most likely hang on to it for the times I need a wideish zoom. I would also keep my 55-300, as it's a great lens for those times where I need more than 100mm (my longest prime at this time). If I do go this route, then I would simply start adding DA ltds, so that my collection would look like this: 15 (when it comes out), 21, 35 (I already have), and 70. I would sell the 12-24 and 50; I'm not sure about the 28-75 yet.
For those of you who are wondering, I do plan on keeping my LBA challenge commitment.
I'll just keep using my lenses I have, making note of which focal lengths I use the most and see where that leads me.
Thanks for all the help!
Heather