I can't say I have worn a fanny belt since the early 90's.
Back then, as we cruised around on our rigid bikes with BLT Lights, double water bottle holders, (one with the battery for the lights in it), bar ends with Ritchey grips (put on backwards, of course) and there was little space in the underseat bag, so we used fanny bags to hold all the various stuff that we needed.
Flash forward close to thirty years and it seems belt bags are starting to make a comeback.
I tried out the Camelbak Podium Flow Belt and it is a very well designed bag.
It has a total capacity of 2.5L including the water bottle, or 2L of cargo space. That space is broken up into a quick access zippered pocket, the main pocket with two mesh pockets for tools or other small pieces and the water bottle holder.
The water bottle sits on the right side and is positioned on an angle somewhere around 1pm as to make getting it in and out easier. Works very well, unless you are a lefty and it's your harder side. Camelbak has a new bottle called the Podium Dirt series that pairs with it perfectly and has a smart top on it to prevent getting dirt on the mouth piece. The whole cap assembly comes apart for cleaning, and the whole thing can go in the dishwasher, albeit on the upper rack.
I'm not sure they could have made the pack any lighter as it comes in at 190 grams, or six ounces. That translates well to the trail as you barely notice the weight of the pack and it stays in place nicely while riding. I"m not sure I would take it in the bike park, but if you are on a multi hour ride, it's the perfect size.
Price: $69.99 cdn