C700 vs SA6 comparo
Now, I'll be the first to admit this isn't quite an apples to apples comparison.

First off, we are talking a canalphone vs IEM and there is quite a price difference. Regardless, I figured why the heck not especially since I really like the C700s... a lot.

I will summarize the below by saying I felt the SA6 bested the C700s pretty much across the board. If you want more detail, read on.
Isolation is crazy good with the SA6. Of course this comes at no surprise due to the differing formats but for those of you who also have experience with FS' Atrio M5s, the SA6s isolate more.
Soundstage is rather disorienting with the SA6. Where I find if listening to classical music with the C700s, I hear about 120 degree breadth of full orchestra sound which is pretty darn good. The SA6 are more like 160, maybe even 170. And the SA6 sound like headphones rather than earphones to me. Takes some getting used to actually.
Bass - at first it seemed like the Denons were favorable. And it was more pronounced. I then put in the Bass + port on the SA6 and the bass came forward. I found the SA6 to offer more controlled and defined bass. Not a night/day difference but certainly noticeable.
Midrange - this was probably the biggest difference between the two. And I think it really has to do with the lower mids. They are more present, richer with the SA6. In direct comparison, violas on the C700s sounded empty and hollow. And vocals lacked depth. It was rather surprising since I've always tagged the C700s as warm and musical sounding. But jumping between the two earphones, the difference was rather remarkable.
Highs - I installed the Treble + port on my SA6 which really gave them some sparkle with zero harshness. The Denons' rolled off highs were very apparent in direct comparison.
The C700s did pretty well in regards to instrument separation, placement and overall detail. I would give only a slight edge to the SA6.
The above was done using my Trekstor Vibez as a source which I have nothing but 320bps Lame encoded MP3s. Certainly not the ultimate in source but it is what I use with my earphones so...
Further disclosure: I have the genuine Sony EX tips on my Denons and I was using Sleek Audio's stock bi-flanges on the SA6.
And for those who may be interested, I'll be posting an Atrio M5 vs SA6 comparo over on that thread in the next day or two.