I am close to the mixing stage so I can't comment there as of yet. The current project I'm working on now is at 96khz. I'm not having any difficulty at all recording. I don't monitor what I'm doing from Sonar, just from the OC itself. Zero issues there.
I have noticed that it seems smoother at 96khz. I'll have to get back to you on that because it may be where I had it located. It made a little noise when starting and saving. I moved it from the bad location and then bumped it to 96 and it stopped. I have not tried the 44.1 I usually used since I moved it.
I don't like that all the features are not available from the UI in the control panel. You have to change the sample rate on the OC itself. Not a huge deal but it would be nice to do it on the UI in control panel.
I really like the compressor/gate it comes with. I use as little ratio for the compressor but I mainly use the gate to quiet the noisy guitar. The gate is very clean and the compressor is transparent. I tried using the gate on my E-MU 1616m and it never sounded good. I never used it. The reverb on the OC is very usable. You can't record it but for tracking, it's very good.
If you look at other posts by me about the OC, I've posted other things that I've done with it.
If you spent $800 on a Lynx though, why not spend a little more and get an RME? Everyone here says they are THE best. Their second best was the OC though.
Good luck!