12800 iso will look like a cat vomit after eating a pack of m&ms
THAT made me LOL!!
I've never heard that as a description of high noise, but it's very apt!
I've used the SL1 (in store) for about 5 minutes the other week and then I also tried the 700D in store too. So I couldn't really determine the noise to any great detail, but both did seem fairly close to my 7D (judging from the screens and zooming in).
Hopefully Canon will introduce a new, improved sensor with the 7DmkII (and even better, if it is included in the 70D). As I'm not planning on getting a 70D, but rather a 7DmkII (or mkIII) if / when my 7D is due for replacement, I do hope Canon achieves advances in their sensor technology over the next few releases, both the 70D and 7Dmkxx. I'm very happy with my 7D, and have used a number of xxD cameras too, and still have my old 350D as a backup.
Regarding swivel screen- if it's 'quite solid' when locked in, I'm all for that, at times (especially with macros or some positions) - having a swivel screen using live view can be helpful (and I don't own a smart phone... yet)...
I am sure the 70D will be a great enthusiast camera, hopefully they will include AFMA with it, and a robust AF system - these are 2 things I think that level of camera deserve.