Viola tension problems?

I've had problems with the Kun rests lately too. I have one that I bought for my violin about 5 years ago, and I love it. It grips my violin really well and the foam is sooo comfortable! Last summer I bought a Kun for my viola, but I really don't like it. They use a different material for the feet now so it's always slipping off my viola, and they use a different foam now that's thinner and not as cushy and really uncomfortable! So I think I need to go back to my violin shop and try out some new ones, which you should do too. It's the best way to find out which one is the most comfortable. Some violists prefer not using one, but people with longer necks usually find this uncomfortable.