Uniflow has been proved absolutely to provide more uniform engine runs, especially when the model experiences high g loads. How it works is a lot of fun to discuss, but how it performs is documented. It solves engine run problems and has for years and years.

Having the pressure line outlet into the tank in close proximity to the fuel pickup point in the tank insures that the pressure the pickup point sees is constant. Or almost constant.

There are a couple of model airplane competitions that have proven uniflow setups work, and prove it over and over and over and.....