The short answer is EPO would benefit a recreational athlete exactly the same as a professional athlete. It increases oxygen carrying capacity by a fixed amount. That will increase performance regardless of your fitness level. <<
It’s not quite that linear. The key to EPO is that it stimulates RBC production. RBC carry O2 to the muscles and help in recovery. So EPO allows you to train longer and harder than you otherwise would be able to, provided you have the time to do so. Many AGer’s would not fully benefit from EPO use simply because they do not have the time to train. But many do. This is not a problem for Pros.
A main limiter of RBC production is the amount of available Iron (Fe) in your system, Iron is needed to make the oxygen carrying protein of the red blood cells, hemoglobin. You need to take large amounts of Iron to get the full benefit of EPO.
Iron is poisonous to your body as the body has no natural means of getting rid of it. Your body continues to store it in the reticulo-endothelial cells of the liver as well as in other organs, and these organs are the most affected by a large intake of iron. Iron is also dangerous as in solution it has corrosive properties, which can damage your GI tract.
If you don’t have the time to put in huge days, EPO will be moderately effective, and if you don’t have the ability to have blood work done regularly EPO will kill you. Plus in the long term you are gambling with your liver. Risk vs. reward is very high.