Not without reason extensions from Peter van Westen are one of the top-rated extension here.
Tabber works really fine - it is well thought and has a very "understandable" Documentation (for me). Perfect Support via eMail and simple Updates via NoNumer Extension manager.
But what i REALLY appreciate is, that you can try ALL NoNmber extensions FREE OF CHARGE without any limitations. And if you are satisfied just buy a license to support his great work ! Keep It on!