No experience w/ Ibex, but I bought the SW liners as a gift and found they run large. I usually wear men's large in most gloves, cycling included, and easily fit in the medium SW. In general I think glove sizing can be the most crazy-making of any apparel -- I've yet to find a size chart that accurately predicts my size. Partially because I have narrow hands compared to the length of my fingers, I guess, but I rarely buy if I haven't tried them on first.

Unless you have a loose outer glove I'd think twice about using them as a liner though, because they're relatively thick and I get colder hands with a liner if inner/outer fits snug.

My favorite liner by far, even though I end up having to replace them almost every year, is the Seirus Outlast Superliner Gloves. I'm generally a natural fibers person, but these are very thin and incredibly warm for their weight. They're so good for so many of my activities that I find them a good value despite the needed replacement.