Never had any issues with Weber. I changed about 1 year ago from BAL. I trust this brand as their tiling product range contains the best tiling knowledge I have ever seen and their products are very, very sound as I see. Bear it in mind that Saint Gobain make their products, and they are one of the biggest companies in the world - they wouldn't launch a bad product.
Saint Gobain also own Graham's. The worst (so called) plumbers merchant.
Grouted these mosaics this morning with Weber Joint.Pro - Silver Grey. Nice stuff to work with actually.