I had a filmjolk (sorry, I don't know how to make the umlaut) starter that I got from a friend, and while I was using that the result was thick and smooth, much less lumpy than kefir has ever been when I've made it, tart but not as sour/yeasty as kefir, more like a yogurt flavor. I loved it. I made the filmjolk with full-fat raw milk straight out of the refrigerator, left to culture on the counter for about 12 hours, the temp in my house is usually between 65-80 degrees F (depending on season). That culture only lasted about 6 or 8 months, and then it seemed to fizzle out, or maybe got out-competed by the other organisms in the raw milk, it wouldn't thicken as much anymore, had more of a plain sour milk flavor, and separated into curds and whey more readily instead of being a thick, smooth texture. I don't have a new filmjolk culture yet, I stopped trying to use the old one because I didn't like it that way. My friend who gave me the culture originally said she's had to order a new culture several times, that the filmjolk culture is more like yogurt in that you need to periodically get a "clean" starter to keep the characteristics the same. Kefir is more durable and consistent, but I just don't like it as well as filmjolk.
