I used Seafoam in the tank on my last trip over Thanksgiving and it seems to do about 75% of the job of BG44k...which means for me that it outperforms BG44k since it's about 1/3 of the price. By "job", I mean taking care of the vibration and noise in gear. Mileage probably went up slightly as a side-effect of the cleaning, but that's not why I seek out an infrequent tank solution.
However, if you are looking for an annual product to easily run through your fuel system, try to track down a bottle of 44k. Might be easiest to pick some up on eBay since, for some reason, it's IMPOSSIBLE to find locally.