As an owner of the K10s and the 846s, I agree completely. As I said earlier in this thread (I think it was this one...) the 846 is phenomenal, but I think the K10 still edges it out in the overall package. The K10 is definitely not missing out at all in the bass. If it's called for in the recording, the K10 will bring it out no problem. Actually, I slightly prefer the bass on the K10 to the bass on the 846; the "subwoofer effect" on the 846 is really nice when I'm in the mood for it, but I am finding that the K10 is the headphone I always reach for first. I would definitely say that the 846 is a warmer overall presentation than the K10; if that's your style, you may prefer it.
For me, the only limiting factor is my lack of ears. That being said, I do reach for the K10 more often than the 846. To my ears, everything sounds just a bit more natural and a bit more enjoyable. With the K10, I feel like I'm listening to the music. With the 846, I feel like I'm listening to the 846. Not that that is at all bad, and I actually enjoy doing that, too. It's just that, if I had to pick one, it'd be the K10. If I already had the 846, though, and I would have to sell it to fund a K10, I might not be so quick to jump the gun. The 846 is damn impressive, and I don't really know if the slight improvements of the K10 are worth a nearly doubling in price to get them.
Further, not only do the K10 and the 8C have the same bass drivers (and the 8C and K10 share 8 drivers in common; the K10 has an extra 2 drivers compared with the 8C), the 5/5C/5S has **one** of the **two** bass drivers that is found in the 8C/K10. I would be surprised if the overall quality and quantity of the K10 or 8C were lacking, especially compared to the 5C (which I haven't yet heard, so I can't do a direct comparison). To my ears, with a fully custom fit (and perfectly fitting, I might add) K10 and the universal fit 846, I find that the K10 has both more quality and more quantity to bass when it is called for, with the caveat being that it's only there when it is called for; it's not always present if it's not in the recording, while the 846 to my ear seems to add just a bit of warmth. It's just that the K10 isn't a bass-emphasized tuning.