I've been using a Clarisea SK-5000 for 3 months. It a fantastic piece of equipment. I don't have any experience with a Thieling Rollermat.
Prior to purchasing the Clarisea, I was a little nervous about plumbing it into the main drain of a Bean Animal Overflow. I was concerned that it would mess-up the drains balance; this hasn't been an issue.
In retrospect, I went a little oversized with the SK-5000 and a SK-3000 would likely have been better for my tank size and sump flow (100 gallons total volume). In 3 months, I've only used 1/2 of one roll. It advances multiple times a day and takes the entire flow. The price difference between the 3000 and 5000 are very small, if I was repurchasing it, since I have the space in my sump, I would still buy the 5000 again.
I'm honestly surprised to see all the threads about the Klir. Based on reading the issues on those threads, the Clarisea seems to be a superior build and with a greater roll capacity. I do understand the convenience of dropping it into a sock holder, but it still seems like a disproportionate number of people post on the Klir, where I found very few posts on the Clarisea when I was doing my pre-purchase research.
Lastly, I wouldn't recommend the manual Clarisea, you save a little money but it defeats what I think is the best part - automation.
Hope this helps.
-Pete