Interesting - One of your main photographic tastes has concentrated around landscape. Can I ask what took you into the phase of experimenting with wide aperture primes (In my mind used for shallow DOF)?
Certainly
I've recently been shooting events far more than landscapes; plenty of festivals, theatre and community events plus an occasional wedding.
These frequently involve candid subjects with moving people in poor light, focussing is often a challenge, even with the big camera
The X10 is way out of it's depth and badly struggles with focus.
Plus I like the cinematic look that shallow DoF gives
As an experiment I shot an entire festival with just a 300mm prime and an 8-15 fisheye; looking at the gallery thumbnails my images stand out - which is what I was hoping for
Here's an example gallery with work by several photograhers, you should easily be able to see what I mean -
http://www.priddyfolk.org/cpg/thumbnails.php?album=9
I've not upgraded the X10 because I'm frequently pushing the abilities of the 5DIII and although the X20 would be loads better, it would still be no match for the 5DIII and a decent prime.
However, I've usually got the X10 close at hand, just in case - and I know it'll do me proud.
Edited to add...
The X10's portability would sometimes be far more appropriate!
Here's a piccy of me descending a huge slide trying to protect the 5DII and 8-15 fisheye.
http://www.priddyfolk.org/cpg/displayimage.php?album=9&pid=951#top_display_media
In the filmstrip at the bottom of that page you can see some images I took while I was up there.
This summer I also ended up going down a zip-wire with the 5DIII hand-held (no backpack).
As they say - don't try this at home....