With the media I normally use, I haven't seen any problems with media compatibility or writing quality. Media that worked at 52x on the LTR-52246S work at the same speed on the 7S. Of course, that's my media.
Yes, K-Probe works with the drive. Here too, the results are comparable to the LTR-52246S
"Blu-ray is just a bag of hurt." - Steve Jobs