I don't think the layering possibility should be a deciding point, as you can do it with most soak off gels.
Sam Biddle did comparre a lot of these sytems and it may help you to read her. otherwise, go to some distributors and make a decision for yourself considering price, color range, client...
Gigi, I have to say it again, but I love you for saying this (and the rest in this thread)
I use tips cuz at times they can be time savers... they're my best friends, esp the new generation, white, matte, with a nice smile line.